Studio: movable areas and workspaces in Frame Studio's own Blender-like style

- ImGui's docking branch (1.91.5): the 3D Viewport, Outliner, Properties and Timeline are areas on a gutter, each with a header. Drag an area by its header's editor button to dock it elsewhere (as a tab, or splitting an area); click it to show another editor there. Layouts are kept between runs; Window > Reset Layout restores them. - Workspaces in the top bar: Layout, Walking, Headset. Ctrl+Space maximizes the 3D Viewport. - 3D Viewport header: Arrange / Draw Floor, View, Select, Add, Object menus, Global / Local, the world layer and shading (Material, Solid, Wireframe; GPU Cost, Overdraw, Leave Out in its menu). In the view: the toolbar (T), a chip naming the home and selection, navigation buttons under the axes, a sidebar (N: Item, Tool, View). - Properties: tabs as icons down its left edge (Object, World, Environment, Bundle, Headset); sections are panels on lighter boxes; labels right-aligned in a column. Sound is part of the Environment tab. - Timeline: transport in its header, a ruler in seconds with the playhead. Status bar: what the mouse does. - Keys: Shift+A add menu, X asks before deleting, F3 menu search, Alt+A, Space, Numpad 1/3/7 views, T, N. - Inter (SIL OFL) built in as the interface font; a palette of cool greys, one blue, Frame Studio's orange. - ImGui patches (marked Frame Studio): the submenu triangle, and dropdown arrows drawn small on the field. - Self-test: an area dragged to dock elsewhere, Reset Layout, workspaces, F3 (104/104). - Guides follow the new menus. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-28 21:02:20 +01:00 · 2026-10-21 14:14:46 -05:00
1 parent e9d670b755
commit b0609d3664
@@ -13,7 +13,7 @@ headset runs, and lets you edit, save and send them to the headset.
 2. **Prepare the headset** once: developer mode, SSH and a key. See [Preparing the Steam Frame](docs/headset-setup.md).
 3. **Install Frame Home**: in Studio, **Headset > Install on Steam Frame...**, then **Install Frame Home**.
   See [Installing Frame Home](docs/install-frame-home.md).
-4. **Open a home**: **File > Open Home...** and pick a Meta home `.apk`, a `.fenv` or a model.
+4. **Open a home**: **File > Open...** and pick a Meta home `.apk`, a `.fenv` or a model.
 5. **Send it**: **Headset > Send to Frame**. Put the headset on: you are standing in it.

 ## Downloads
@@ -106,7 +106,8 @@ Frame Studio and Frame Home are licensed under the **GNU Affero General Public L
 You may use, study, change and share them; if you share a changed version, or run one for others over a network,
 its source must be available under the same license.

-Vendored libraries in `third_party/` keep their own licenses (in each folder). The home loaders in `third_party/qhe`
+Vendored libraries in `third_party/` keep their own licenses (in each folder); Studio's interface font, Inter, is under
+the SIL Open Font License (`third_party/inter/LICENSE.txt`). The home loaders in `third_party/qhe`
 started from Quest Home Editor and keep its MIT license for the original code; see
 [third_party/qhe/LICENSE.md](third_party/qhe/LICENSE.md).

@@ -6,9 +6,9 @@ files it holds, and the Environments panel lists each one separately.

 ## Making a bundle in Frame Studio

-Everything is in the **Bundle** menu and on the Inspector's **Bundle** tab.
+Everything is in **File > Bundle** and on the **Bundle** tab in Properties.

-1. **Bundle > New Bundle** starts an empty one, and the **Bundle** tab opens.
+1. **File > Bundle > New Bundle** starts an empty one, and the **Bundle** tab opens.
 2. Give it a **Name**. It's the bundle's own name; each environment keeps its name.
 3. Add environments:
   - **Add the Open Environment**: the environment you have open, as it was last saved. Save first (Ctrl+S) to
@@ -24,7 +24,7 @@ Everything is in the **Bundle** menu and on the Inspector's **Bundle** tab.

 ## Opening a bundle

-**Bundle > Open Bundle...**, **File > Open Home...**, or dropping a `.fbundle` on the window opens the bundle on the
+**File > Bundle > Open Bundle...**, **File > Open...**, or dropping a `.fbundle` on the window opens the bundle on the
 Bundle tab. Its environments are listed in place; nothing is unpacked yet.

 - Double-click an environment to open it. It is unpacked into a scratch folder first.
@@ -49,7 +49,7 @@ A home with a room and its vista is usually larger than either alone.

 ## Making a .fenv in Frame Studio

-1. Open a home: **File > Open Home...**.
+1. Open a home: **File > Open...**.
 2. Edit it if you like.
 3. **File > Save to My Environments** (Ctrl+S) or **File > Save As...**.

@@ -129,7 +129,7 @@ Prints the name, baked or wrapped, its sources and models, whether it has edits
 ```

 Lists what the home is made of, what it costs, and problems found. It ends with exit code 3 when the home is broken.
-Studio shows the same under **Debug > Home Report...**.
+Studio shows the same under **Window > Home Report...**.

 ## Per-world settings

@@ -115,10 +115,10 @@ Before you start, set up the headset once: [headset-setup.md](headset-setup.md).

 ### 1. Open a home

-1. Choose **File > Open Home...** (Ctrl+O), or drop files onto the Studio window.
+1. Choose **File > Open...** (Ctrl+O), or drop files onto the Studio window.
 2. Pick a Meta home (`.apk`), a `.fenv` environment, or a model.
   - To open a room together with its view outside (a "footprint" and a "vista"), select both files in the dialog.
-     You can also add a vista later with **File > Add Vista...**.
+     You can also add a vista later with **File > Import > Vista...**.
 3. Wait for the home to load. Studio shows its progress.

 ### 2. Look around
@@ -134,8 +134,9 @@ Before you start, set up the headset once: [headset-setup.md](headset-setup.md).

 **Help > Controls** (F1) lists every shortcut.

-To change something, select an object, then use **Edit > Move** (G), **Rotate** (R), **Scale** (S), **Hide
-Selected** (H) or **Delete Selected** (X). The selected object's details show in the Inspector on the right.
+To change something, select an object, then pick **Move** (G), **Rotate** (R) or **Scale** (S) in the toolbar on the
+left of the view and drag the gizmo, or use **Object > Show/Hide** (H) or **Object > Delete** (X). The selected
+object's details show in Properties, on the right. Shift+A adds things where you look; F3 finds any command.
 **Edit > Undo** (Ctrl+Z) takes any step back.

 ### 3. Save
@@ -8,7 +8,7 @@ Before you start, the headset needs developer mode and SSH: see [headset-setup.m

 ## Way 1: from Frame Studio

-1. Open the Inspector's **Headset** tab (on the right), or choose **Headset > Install on Steam Frame...**, which opens it.
+1. Open the **Headset** tab in Properties (on the right), or choose **Headset > Install on Steam Frame...**, which opens it.
 2. In **Headset**, type the headset's address: an SSH alias such as `frame`, or `steamos@<address>`, for example
   `steamos@192.168.1.50`. Studio remembers it.
 3. Under **Environments to install**, choose what to copy along:
@@ -27,7 +27,7 @@ lower Resolution"**, frames are late.

 The **Debug** page helps find what is slow:

- **View > GPU cost** tints each mesh: green is cheap, red is costly.
+- The 3D Viewport's shading menu (▾ at the right of its header) **> GPU Cost** tints each mesh: green is cheap, red is costly.
 - **Costliest meshes** lists the most expensive ones.
 - **Leave out** See-through surfaces, Cut-out surfaces or Sky shows whether those are what's slow.

@@ -35,11 +35,11 @@ See [using-frame-home.md](using-frame-home.md#the-debug-page).

 ### From your computer

- In Studio, **Edit > Settings...** shows "Now on the headset: ..." under the Steam Frame settings, read from the
+- In Studio, **Edit > Preferences...** shows "Now on the headset: ..." under the Steam Frame settings, read from the
  headset. **Read from Headset** refreshes it.
- **Debug > Headset Debug...** shows and changes the headset's Debug page.
- **Debug > Home Report...** lists what the open home costs and what's wrong with it.
- Studio's own **Debug** views (Normal, Wireframe, Meshes, GPU Cost, Overdraw) and **Debug > Leave Out** work like the
+- **Headset > Headset Debug...** shows and changes the headset's Debug page.
+- **Window > Home Report...** lists what the open home costs and what's wrong with it.
+- Studio's viewport shading (Material, Wireframe, Solid, GPU Cost, Overdraw, and **Leave Out** in its ▾ menu) works like the
  headset's, but they measure your computer's GPU, not the headset's.

 On the headset, Frame Home writes its numbers to `~/frame-home/stats.json` every 2 seconds (GPU and CPU time per
@@ -90,7 +90,7 @@ Studio tries not to use your computer more than it needs to:
 - It draws at your display's refresh rate while its window has focus, and at 30 fps when it doesn't.
 - When nothing changes (no input for a second and nothing moving by itself), it stops drawing and waits for input.
  Playing animations, loading and saving keep it drawing.
- **Edit > Settings...** under "This PC (Frame Studio)" has Viewport resolution, Anti-aliasing, Texture limit and
+- **Edit > Preferences...** under "This PC (Frame Studio)" has Viewport resolution, Anti-aliasing, Texture limit and
  Texture filtering for big homes on slower computers.

 Two environment variables help when measuring:
@@ -7,44 +7,54 @@ the headset. This guide walks through the window and the everyday tasks. To inst

 ## The window

+Frame Studio is laid out the way Blender works: the window is split into **areas**, each showing one editor, with
+a header along its top.
+
 ```
-┌───────────────────────────────────────────────────────────────────────────┐
-│ File  Edit  View  World  Bundle  Headset  Debug  Help         menu bar     │
-├────┬──────────────┬──────────────────────────────┬────────────────────────┤
-│ ✥  │ EXPLORER     │                              │ Selected World Env… … │
-│ ⟳  │ Filter…      │                              │ ───────────────────── │
-│ ⤢  │ ▾ Root       │          3D VIEW             │      INSPECTOR         │
-│ ✎  │   ▾ folder   │                              │  (the chosen tab's     │
-│ ── │     object   │                              │   settings)            │
-│ ◍  │ ▾ World      │                              │                        │
-│ ☺  │   Spawns …   │                              │                        │
-│ ⌗  │              │                              │                        │
-├────┴──────────────┴──────────────────────────────┴────────────────────────┤
-│ ❚❚ Pause  ───────────●─────────────────  12.0 / 60.0 s          Sound on   │
-│ Home name · format · selection · fps                      Frame: sent …    │
-└───────────────────────────────────────────────────────────────────────────┘
+┌────────────────────────────────────────────────────────────────────────────┐
+│ ◎ File Edit Headset Window Help │ Layout  Walking  Headset │    home name    │  top bar
+├──────────────────────────────────────────────────────┬─────────────────────┤
+│ ▣▾ Arrange▾ View Select Add Object  Global▾   ◈ ◯◯◯▾  │ ☰▾ As in the File▾ 🔍 │
+│ ┌──┐ ● home › selection                       (axes) │ ▾ Root               │
+│ │✥ │                                            🔍   │   ▾ folder         👁 │
+│ │⟳ │              3D VIEWPORT                   ✋   │     object         👁 │  Outliner
+│ │⤢ │                                            👤   ├─────────────────────┤
+│ │✎ │                                            ⤢   │ 🔧▾ Object           │
+│ └──┘                                                 │ ■ │ ▾ Object         │
+│  (toolbar: T)                     (sidebar: N) ▸     │ 👣│  Location  …      │  Properties
+├──────────────────────────────────────────────────────┤ ▣ │ ▾ Surface        │
+│ 🕐▾ Playback▾          ⏮ ▶ ⏭          12.0 / 60.0 s 🔊 │ ▤ │   …              │
+│ 0    5    10 ▮12.0  15    20    25    30    …       │ ⌂ │                  │  Timeline
+├──────────────────────────────────────────────────────┴─────────────────────┤
+│ 🖱 Select  🖱 Rotate View  🖱 Context Menu / Fly        182 objects | 60 fps │  status bar
+└────────────────────────────────────────────────────────────────────────────┘
 ```

-| Part | Where | What it's for |
-|---|---|---|
-| **Tool strip** | left edge | the transform tools, Draw Floor, and how the gizmo and the camera behave |
-| **Explorer** | left | everything in the home: its objects (in the file's own folders, or grouped by kind) and its world items |
-| **3D view** | middle | the home as the headset draws it, with the gizmo and the walkable area on top |
-| **Inspector** | right | settings, in tabs: **Selected**, **World**, **Environment**, **Bundle**, **Headset** |
-| **Timeline** | bottom | plays the home's animations and sound; drag to scrub through the loop |
-| **Status bar** | very bottom | the home's name and format, what's selected, the frame rate, and whether the headset has it |
+| Area | What it's for |
+|---|---|
+| **3D Viewport** | the home as the headset draws it. Its header has the mode (Arrange or Draw Floor), the **View**, **Select**, **Add** and **Object** menus, the gizmo's orientation (Global or Local), the world layer and the shading (Wireframe, Solid, Material, more in ▾). Inside it: the toolbar (T), the axes and navigation buttons, and the sidebar (N) |
+| **Outliner** | everything in the home: its objects (as the file lays them out, or by kind) and its world items, with an eye to hide each |
+| **Properties** | settings, in tabs down its left edge: **Object** (what you selected), **World** (where you can walk), **Environment** (name, picture, sound, headset settings), **Bundle**, **Headset** |
+| **Timeline** | plays the home's animations and sound; click or drag in it to scrub through the loop |

-Drag the thin lines between the Explorer, the 3D view and the Inspector to make any of them wider.
+**Rearranging areas.** Drag the gutter between two areas to resize them. To move an area, drag the **editor button**
+at the left of its header (the icon with ▾) and drop it on another area: onto its middle to stack them as tabs, or
+onto an edge to split that area. Click the editor button to show a different editor in that area. **Window > Reset
+Layout** puts everything back; **Ctrl+Space** fills the window with the 3D Viewport until you press it again.
+
+**Workspaces.** The tabs in the top bar switch between layouts made for a job: **Layout** (everything), **Walking**
+(a big view with Properties on the World tab) and **Headset** (Properties on the Headset tab). Studio remembers
+your layout between runs.

 ## Opening a home

- **File > Open Home...** (Ctrl+O), or drop a file on the window. It opens:
+- **File > Open...** (Ctrl+O), or drop a file on the window. It opens:
  - a Meta home (`.apk`). A *footprint* (the room) and its *vista* (the world outside) are opened together: pick both
    in the file dialog, or open the footprint and Studio offers the vistas beside it;
  - a Frame environment (`.fenv`);
  - models from Blender or Unity (`.glb`, `.gltf`, `.fbx`, `.obj`).
 - **File > My Environments** lists what you have saved; **File > Open Recent** lists what you had open.
- **File > Add Vista...** gives a footprint its vista; **File > Add Models...** places models into the home.
+- **File > Import > Vista...** gives a footprint its vista; **File > Import > Models...** places models into the home.
 - A big home asks after a while whether to keep waiting; **Stop Loading** cancels.

 ## Moving around in the 3D view
@@ -55,22 +65,22 @@ Drag the thin lines between the Explorer, the 3D view and the Inspector to make
 | Pan | Shift + middle-drag |
 | Zoom | mouse wheel, or Ctrl + middle-drag |
 | Fly | hold the right mouse button + W A S D, Q / E down / up (wheel: speed, Shift: 4x) |
-| Look from where you'd stand | **Player view** in the tool strip, P, or Numpad 0 |
-| Frame the selection / everything | F / Home (or double-click a row in the Explorer) |
+| Look from where you'd stand | the person button under the axes, P, or Numpad 0 |
+| Frame the selection / everything | F or Numpad . / Home (or double-click a row in the Outliner) |

 Press **F1** (Help > Controls) for the full list.

 ## Selecting and editing objects

-1. Click an object in the 3D view or the Explorer. The Inspector switches to **Selected**.
-2. Pick a tool in the tool strip (or press its key) and drag the gizmo:
+1. Click an object in the 3D view or the Outliner. Properties switches to its **Object** tab.
+2. Pick a tool in the toolbar on the left of the view (or press its key) and drag the gizmo:
   - **Move** (G), **Rotate** (R), **Scale** (S). Hold Ctrl to snap.
-   - The globe / cube button switches the gizmo between the world's axes and the object's own.
-3. Or type exact values in **Location**, **Rotation** and **Scale** in the Selected tab.
+   - **Global** / **Local** in the header switches the gizmo between the world's axes and the object's own.
+3. Or type exact values in **Location**, **Rotation** and **Scale** in the Object tab.
 4. In the same tab: **Visible**, **Reset** (back to where the home had it), **Only This** (hide everything else,
   I), and **Delete** (X).

-The Explorer's eye buttons hide objects or whole folders. **Edit > Unhide All** (Alt+H) brings them back. Every
+The Outliner's eye buttons hide objects or whole folders. **Select > Reveal Hidden** (Alt+H) brings them back. Every
 change can be undone with Ctrl+Z and redone with Ctrl+Shift+Z.

 ## Where you can walk
@@ -81,18 +91,18 @@ edges, grey are floors you can't reach. **W** shows or hides it.

 - The **World** tab shows the area's size and its settings (step height, headroom, body radius). The presets
  **Open**, **Standard** and **Careful** set them for you.
- **World > Auto-generate Walkable Surfaces** gives every mesh a surface: walkable where it's flat, blocking where
+- **Object > Auto-generate Walkable Surfaces** (in the 3D Viewport's header) gives every mesh a surface: walkable where it's flat, blocking where
  it's steep. A summary shows what it did; **Undo** in it takes back just that run.
- Per object, the **Surface** buttons in the Selected tab decide what it is for the player:
+- Per object, the **Surface** buttons in the Object tab decide what it is for the player:
  **Auto** (decided by its shape), **Surface** (walk on its flat parts, bump into its steep ones),
  **Collider** (you can't walk through it), **Walk through** (ignored). Right-clicking an object offers the same.
- **Draw Floor** (B, or the brush in the tool strip): select an object, then drag over it to paint walkable floor
+- **Draw Floor** (B, the brush in the toolbar, or the **Draw Floor** mode in the header): select an object, then drag over it to paint walkable floor
  onto it, even on furniture. Shift+drag erases; [ and ] change the brush size. **Fill Flat Faces** paints every face
  of it that's flat enough at once.

 ## World items

-**World > Add at the View's Centre** places items where the camera looks:
+**Add** (in the 3D Viewport's header, or Shift+A over the view) places items where the camera looks:

 | Item | What it does on the headset |
 |---|---|
@@ -104,11 +114,11 @@ edges, grey are floors you can't reach. **W** shows or hides it.
 | **Invisible Wall** | stops you; never drawn on the headset. Scale and turn it to fit; where it stands is no longer walkable |
 | **Gravity Zone** | inside it, "down" is the zone's own: a direction, or any surface you stand on |

-Select an item to move it with the gizmo or type its values in the Selected tab. **World > Clear World Layer**
+Select an item to move it with the gizmo or type its values in the Object tab. **Object > Clear World Layer**
 removes them all.

 Meta's own homes have invisible walls too, round their play space (Cascadia, Space Station, Desert Terrace, Haven).
-Frame Studio and Frame Home read them as invisible walls, so you can't walk out past them. Select one in the Explorer
+Frame Studio and Frame Home read them as invisible walls, so you can't walk out past them. Select one in the Outliner
 to delete it, or set its **Role** to Surface, if you want to go further in that home.

 ## The environment: name, picture, sound
@@ -139,7 +149,7 @@ Saved environments are *baked*: everything the headset needs, already in its own
 ## Bundles

 A bundle (`.fbundle`) packs several saved environments into one file, to share or install together. Use the
-**Bundle** menu or the **Bundle** tab: **New Bundle**, add environments (the open one, from My Environments, or any
+**File > Bundle** or the **Bundle** tab in Properties: **New Bundle**, add environments (the open one, from My Environments, or any
 `.fenv`), **Save Bundle...**, and **Install on Steam Frame...**. Opening a `.fbundle` lists what's in it; double-click
 one to open it, or **Unpack into My Environments**. See [bundles.md](bundles.md).

@@ -155,12 +165,15 @@ The **Headset** tab (or the **Headset** menu):

 ## Settings and tools

- **Edit > Settings...**: Studio's own (3D view resolution, anti-aliasing, texture size and filtering) and the
+- **Edit > Preferences...**: Studio's own (3D view resolution, anti-aliasing, texture size and filtering) and the
  headset's (read from and written to the Frame).
- **Debug**: views that show how the home is built and what it costs (Wireframe, Meshes, GPU Cost, Overdraw),
-  **Leave Out** to hide whole kinds of objects, **Home Report...** (what the home is made of and what may be slow)
-  and **Headset Debug...** (the same views on the headset).
- **View**: **Show Only Selected** (I), **The Home's Meshes**, **World Layer** (W) and **Show Everything**.
+- **Viewport shading** (the buttons and ▾ at the right of the 3D Viewport's header): Material (as the headset draws
+  it), Solid, Wireframe, and in ▾ **GPU Cost**, **Overdraw** and **Leave Out** (hide whole kinds of objects).
+- **Window > Home Report...**: what the home is made of and what may be slow.
+- **Headset > Headset Debug...**: the same views, on the headset.
+- **View** (in the 3D Viewport's header): the toolbar and sidebar, framing, the numpad viewpoints, **Local View**
+  (show only the selection) and **Show Everything**.
+- **Edit > Menu Search...** (F3): find any command by typing part of its name.

 ## Keyboard shortcuts

@@ -168,8 +181,11 @@ The **Headset** tab (or the **Headset** menu):
 |---|---|---|---|
 | Ctrl+O | open | Ctrl+S | save |
 | Ctrl+Shift+S | save as | Ctrl+Z / Ctrl+Shift+Z | undo / redo |
-| G / R / S | move / rotate / scale | B | draw floor |
-| H / Alt+H | hide / unhide all | X, Delete | delete |
-| F / Home | frame selected / all | P, Numpad 0 | player view |
-| I | show only selected | W | world layer |
-| Esc | deselect | F1 | controls |
+| G / R / S | move / rotate / scale tool | B | draw floor |
+| Shift+A | add menu at the mouse | X | delete (asks first); Delete: right away |
+| H / Alt+H | hide / reveal hidden | Alt+A, Esc | select nothing |
+| Numpad . / Home | frame selected / all | Numpad 0, P | player view |
+| Numpad 1 / 3 / 7 | front / right / top (Ctrl: the other side) | Numpad /, I | show only selected |
+| W | world layer | Space | play / pause |
+| T / N | toolbar / sidebar | Ctrl+Space | maximize the 3D Viewport |
+| F3 | menu search: every command by name | F1 | controls |
@@ -32,11 +32,12 @@ If Studio starts but says it couldn't start Vulkan, the message names the `studi

 ## Blank or black view

- With nothing open, Studio shows its start screen. Open a home with **File > Open Home...**.
+- With nothing open, Studio shows its start screen. Open a home with **File > Open...**.
 - A big home takes a while to load; textures arrive after the shapes.
- Check that things aren't hidden: **View > Show Everything**, and **Edit > Unhide All** (Alt+H). **Show Only
-  Selected** (I) hides everything else; press I or Esc to show everything again.
- Make sure **Debug** is set to **Normal** and nothing is ticked under **Debug > Leave Out**.
+- Check that things aren't hidden: **View > Show Everything**, and **Select > Reveal Hidden** (Alt+H). **Local
+  View** (Numpad / or I) shows only the selection; press it again or Esc to show everything.
+- Make sure the view's shading is **Material** (the sphere buttons at the right of the 3D Viewport's header) and
+  nothing is ticked under **▾ > Leave Out**.
 - Use **View > Frame All** (Home key) to bring the whole home into view.

 ## Dialogs don't appear on Linux
@@ -99,7 +99,7 @@ More details:

 ## Settings

-The **Settings** page has three groups. Frame Studio shows the same settings under **Edit > Settings...**, in the
+The **Settings** page has three groups. Frame Studio shows the same settings under **Edit > Preferences...**, in the
 "Steam Frame (Frame Home)" part, so you can change them from your computer too.

 Settings are stored in `~/frame-home/settings.json` on the headset. Frame Home reads it again whenever it changes.
@@ -168,4 +168,4 @@ Frame Home restarts.

 The GPU cost view times every draw, which makes the GPU a little slower while it is on.

-Studio can show and change the same page from your computer: **Debug > Headset Debug...**.
+Studio can show and change the same page from your computer: **Headset > Headset Debug...**.
@@ -128,6 +128,7 @@ target_include_directories(frame-studio PRIVATE
    "${TP}/qhe"
    "${TP}/stb"
    "${TP}/miniaudio"
+    "${TP}/inter"
    "${TP}/acl/includes"
    "${TP}/rtm/includes"
    "${TP}/astcenc/Source"
@@ -9,6 +9,9 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy GLFW_KEY_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
 //  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange' (note: the resizing cursors requires GLFW 3.4+).
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+// Issues:
+//  [ ] Platform: Multi-viewport: ParentViewportID not honored, and so io.ConfigViewportsNoDefaultParent has no effect (minor).

 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -25,6 +28,8 @@

 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2024-11-05: [Docking] Added Linux workaround for spurious mouse up events emitted while dragging and creating new viewport. (#3158, #7733, #7922)
 //  2024-08-22: moved some OS/backend related function pointers from ImGuiIO to ImGuiPlatformIO:
 //               - io.GetClipboardTextFn    -> platform_io.Platform_GetClipboardTextFn
 //               - io.SetClipboardTextFn    -> platform_io.Platform_SetClipboardTextFn
@@ -41,6 +46,7 @@
 //  2023-03-16: Inputs: Fixed key modifiers handling on secondary viewports (docking branch). Broken on 2023/01/04. (#6248, #6034)
 //  2023-03-14: Emscripten: Avoid using glfwGetError() and glfwGetGamepadState() which are not correctly implemented in Emscripten emulation. (#6240)
 //  2023-02-03: Emscripten: Registering custom low-level mouse wheel handler to get more accurate scrolling impulses on Emscripten. (#4019, #6096)
+//  2023-01-18: Handle unsupported glfwGetVideoMode() call on e.g. Emscripten.
 //  2023-01-04: Inputs: Fixed mods state on Linux when using Alt-GR text input (e.g. German keyboard layout), could lead to broken text input. Revert a 2022/01/17 change were we resumed using mods provided by GLFW, turns out they were faulty.
 //  2022-11-22: Perform a dummy glfwGetError() read to cancel missing names with glfwGetKeyName(). (#5908)
 //  2022-10-18: Perform a dummy glfwGetError() read to cancel missing mouse cursors errors. Using GLFW_VERSION_COMBINED directly. (#5785)
@@ -125,11 +131,29 @@

 // We gather version tests as define in order to easily see which features are version-dependent.
 #define GLFW_VERSION_COMBINED           (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 + GLFW_VERSION_REVISION)
+#define GLFW_HAS_WINDOW_TOPMOST         (GLFW_VERSION_COMBINED >= 3200) // 3.2+ GLFW_FLOATING
+#define GLFW_HAS_WINDOW_HOVERED         (GLFW_VERSION_COMBINED >= 3300) // 3.3+ GLFW_HOVERED
+#define GLFW_HAS_WINDOW_ALPHA           (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwSetWindowOpacity
+#define GLFW_HAS_PER_MONITOR_DPI        (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetMonitorContentScale
+#if defined(__EMSCRIPTEN__) || defined(__SWITCH__)                      // no Vulkan support in GLFW for Emscripten or homebrew Nintendo Switch
+#define GLFW_HAS_VULKAN                 (0)
+#else
+#define GLFW_HAS_VULKAN                 (GLFW_VERSION_COMBINED >= 3200) // 3.2+ glfwCreateWindowSurface
+#endif
+#define GLFW_HAS_FOCUS_WINDOW           (GLFW_VERSION_COMBINED >= 3200) // 3.2+ glfwFocusWindow
+#define GLFW_HAS_FOCUS_ON_SHOW          (GLFW_VERSION_COMBINED >= 3300) // 3.3+ GLFW_FOCUS_ON_SHOW
+#define GLFW_HAS_MONITOR_WORK_AREA      (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetMonitorWorkarea
+#define GLFW_HAS_OSX_WINDOW_POS_FIX     (GLFW_VERSION_COMBINED >= 3301) // 3.3.1+ Fixed: Resizing window repositions it on MacOS #1553
 #ifdef GLFW_RESIZE_NESW_CURSOR          // Let's be nice to people who pulled GLFW between 2019-04-16 (3.4 define) and 2019-11-29 (cursors defines) // FIXME: Remove when GLFW 3.4 is released?
 #define GLFW_HAS_NEW_CURSORS            (GLFW_VERSION_COMBINED >= 3400) // 3.4+ GLFW_RESIZE_ALL_CURSOR, GLFW_RESIZE_NESW_CURSOR, GLFW_RESIZE_NWSE_CURSOR, GLFW_NOT_ALLOWED_CURSOR
 #else
 #define GLFW_HAS_NEW_CURSORS            (0)
 #endif
+#ifdef GLFW_MOUSE_PASSTHROUGH           // Let's be nice to people who pulled GLFW between 2019-04-16 (3.4 define) and 2020-07-17 (passthrough)
+#define GLFW_HAS_MOUSE_PASSTHROUGH      (GLFW_VERSION_COMBINED >= 3400) // 3.4+ GLFW_MOUSE_PASSTHROUGH
+#else
+#define GLFW_HAS_MOUSE_PASSTHROUGH      (0)
+#endif
 #define GLFW_HAS_GAMEPAD_API            (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetGamepadState() new api
 #define GLFW_HAS_GETKEYNAME             (GLFW_VERSION_COMBINED >= 3200) // 3.2+ glfwGetKeyName()
 #define GLFW_HAS_GETERROR               (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetError()
@@ -149,9 +173,13 @@ struct ImGui_ImplGlfw_Data
    double                  Time;
    GLFWwindow*             MouseWindow;
    GLFWcursor*             MouseCursors[ImGuiMouseCursor_COUNT];
+    bool                    MouseIgnoreButtonUpWaitForFocusLoss;
+    bool                    MouseIgnoreButtonUp;
    ImVec2                  LastValidMousePos;
+    GLFWwindow*             KeyOwnerWindows[GLFW_KEY_LAST];
    bool                    InstalledCallbacks;
    bool                    CallbacksChainForAllWindows;
+    bool                    WantUpdateMonitors;
 #ifdef EMSCRIPTEN_USE_EMBEDDED_GLFW3
    const char*             CanvasSelector;
 #endif
@@ -184,6 +212,11 @@ static ImGui_ImplGlfw_Data* ImGui_ImplGlfw_GetBackendData()
    return ImGui::GetCurrentContext() ? (ImGui_ImplGlfw_Data*)ImGui::GetIO().BackendPlatformUserData : nullptr;
 }

+// Forward Declarations
+static void ImGui_ImplGlfw_UpdateMonitors();
+static void ImGui_ImplGlfw_InitMultiViewportSupport();
+static void ImGui_ImplGlfw_ShutdownMultiViewportSupport();
+
 // Functions

 // Not static to allow third-party code to use that if they want to (but undocumented)
@@ -337,6 +370,10 @@ void ImGui_ImplGlfw_MouseButtonCallback(GLFWwindow* window, int button, int acti
    if (bd->PrevUserCallbackMousebutton != nullptr && ImGui_ImplGlfw_ShouldChainCallback(window))
        bd->PrevUserCallbackMousebutton(window, button, action, mods);

+    // Workaround for Linux: ignore mouse up events which are following an focus loss following a viewport creation
+    if (bd->MouseIgnoreButtonUp && action == GLFW_RELEASE)
+        return;
+
    ImGui_ImplGlfw_UpdateKeyModifiers(window);

    ImGuiIO& io = ImGui::GetIO();
@@ -404,6 +441,9 @@ void ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int keycode, int scancode, i

    ImGui_ImplGlfw_UpdateKeyModifiers(window);

+    if (keycode >= 0 && keycode < IM_ARRAYSIZE(bd->KeyOwnerWindows))
+        bd->KeyOwnerWindows[keycode] = (action == GLFW_PRESS) ? window : nullptr;
+
    keycode = ImGui_ImplGlfw_TranslateUntranslatedKey(keycode, scancode);

    ImGuiIO& io = ImGui::GetIO();
@@ -418,6 +458,10 @@ void ImGui_ImplGlfw_WindowFocusCallback(GLFWwindow* window, int focused)
    if (bd->PrevUserCallbackWindowFocus != nullptr && ImGui_ImplGlfw_ShouldChainCallback(window))
        bd->PrevUserCallbackWindowFocus(window, focused);

+    // Workaround for Linux: when losing focus with MouseIgnoreButtonUpWaitForFocusLoss set, we will temporarily ignore subsequent Mouse Up events
+    bd->MouseIgnoreButtonUp = (bd->MouseIgnoreButtonUpWaitForFocusLoss && focused == 0);
+    bd->MouseIgnoreButtonUpWaitForFocusLoss = false;
+
    ImGuiIO& io = ImGui::GetIO();
    io.AddFocusEvent(focused != 0);
 }
@@ -429,6 +473,13 @@ void ImGui_ImplGlfw_CursorPosCallback(GLFWwindow* window, double x, double y)
        bd->PrevUserCallbackCursorPos(window, x, y);

    ImGuiIO& io = ImGui::GetIO();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        int window_x, window_y;
+        glfwGetWindowPos(window, &window_x, &window_y);
+        x += window_x;
+        y += window_y;
+    }
    io.AddMousePosEvent((float)x, (float)y);
    bd->LastValidMousePos = ImVec2((float)x, (float)y);
 }
@@ -467,7 +518,8 @@ void ImGui_ImplGlfw_CharCallback(GLFWwindow* window, unsigned int c)

 void ImGui_ImplGlfw_MonitorCallback(GLFWmonitor*, int)
 {
-	// Unused in 'master' branch but 'docking' branch will use this, so we declare it ahead of it so if you have to install callbacks you can install this one too.
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    bd->WantUpdateMonitors = true;
 }

 #ifdef EMSCRIPTEN_USE_EMBEDDED_GLFW3
@@ -489,32 +541,7 @@ static EM_BOOL ImGui_ImplEmscripten_WheelCallback(int, const EmscriptenWheelEven
 #endif

 #ifdef _WIN32
-// GLFW doesn't allow to distinguish Mouse vs TouchScreen vs Pen.
-// Add support for Win32 (based on imgui_impl_win32), because we rely on _TouchScreen info to trickle inputs differently.
-static ImGuiMouseSource GetMouseSourceFromMessageExtraInfo()
-{
-    LPARAM extra_info = ::GetMessageExtraInfo();
-    if ((extra_info & 0xFFFFFF80) == 0xFF515700)
-        return ImGuiMouseSource_Pen;
-    if ((extra_info & 0xFFFFFF80) == 0xFF515780)
-        return ImGuiMouseSource_TouchScreen;
-    return ImGuiMouseSource_Mouse;
-}
-static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
-{
-    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
-    switch (msg)
-    {
-    case WM_MOUSEMOVE: case WM_NCMOUSEMOVE:
-    case WM_LBUTTONDOWN: case WM_LBUTTONDBLCLK: case WM_LBUTTONUP:
-    case WM_RBUTTONDOWN: case WM_RBUTTONDBLCLK: case WM_RBUTTONUP:
-    case WM_MBUTTONDOWN: case WM_MBUTTONDBLCLK: case WM_MBUTTONUP:
-    case WM_XBUTTONDOWN: case WM_XBUTTONDBLCLK: case WM_XBUTTONUP:
-        ImGui::GetIO().AddMouseSourceEvent(GetMouseSourceFromMessageExtraInfo());
-        break;
-    }
-    return ::CallWindowProcW(bd->PrevWndProc, hWnd, msg, wParam, lParam);
-}
+static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 #endif

 void ImGui_ImplGlfw_InstallCallbacks(GLFWwindow* window)
@@ -590,9 +617,16 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
    io.BackendPlatformName = "imgui_impl_glfw";
    io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;         // We can honor GetMouseCursor() values (optional)
    io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
+#ifndef __EMSCRIPTEN__
+    io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;    // We can create multi-viewports on the Platform side (optional)
+#endif
+#if GLFW_HAS_MOUSE_PASSTHROUGH || GLFW_HAS_WINDOW_HOVERED
+    io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport; // We can call io.AddMouseViewportEvent() with correct data (optional)
+#endif

    bd->Window = window;
    bd->Time = 0.0;
+    bd->WantUpdateMonitors = true;

    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
    platform_io.Platform_SetClipboardTextFn = [](ImGuiContext*, const char* text) { glfwSetClipboardString(NULL, text); };
@@ -631,6 +665,11 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
    if (install_callbacks)
        ImGui_ImplGlfw_InstallCallbacks(window);

+    // Update monitor a first time during init
+    // (note: monitor callback are broken in GLFW 3.2 and earlier, see github.com/glfw/glfw/issues/784)
+    ImGui_ImplGlfw_UpdateMonitors();
+    glfwSetMonitorCallback(ImGui_ImplGlfw_MonitorCallback);
+
    // Set platform dependent data in viewport
    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
    main_viewport->PlatformHandle = (void*)bd->Window;
@@ -641,6 +680,7 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
 #else
    IM_UNUSED(main_viewport);
 #endif
+    ImGui_ImplGlfw_InitMultiViewportSupport();

    // Windows: register a WndProc hook so we can intercept some messages.
 #ifdef _WIN32
@@ -691,6 +731,8 @@ void ImGui_ImplGlfw_Shutdown()
    IM_ASSERT(bd != nullptr && "No platform backend to shutdown, or already shutdown?");
    ImGuiIO& io = ImGui::GetIO();

+    ImGui_ImplGlfw_ShutdownMultiViewportSupport();
+
    if (bd->InstalledCallbacks)
        ImGui_ImplGlfw_RestoreCallbacks(bd->Window);
 #ifdef EMSCRIPTEN_USE_EMBEDDED_GLFW3
@@ -710,7 +752,7 @@ void ImGui_ImplGlfw_Shutdown()

    io.BackendPlatformName = nullptr;
    io.BackendPlatformUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad);
+    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
    IM_DELETE(bd);
 }

@@ -718,10 +760,15 @@ static void ImGui_ImplGlfw_UpdateMouseData()
 {
    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
    ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();

-    // (those braces are here to reduce diff with multi-viewports support in 'docking' branch)
+    ImGuiID mouse_viewport_id = 0;
+    const ImVec2 mouse_pos_prev = io.MousePos;
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
    {
-        GLFWwindow* window = bd->Window;
+        ImGuiViewport* viewport = platform_io.Viewports[n];
+        GLFWwindow* window = (GLFWwindow*)viewport->PlatformHandle;
+
 #ifdef EMSCRIPTEN_USE_EMBEDDED_GLFW3
        const bool is_window_focused = true;
 #else
@@ -730,19 +777,54 @@ static void ImGui_ImplGlfw_UpdateMouseData()
        if (is_window_focused)
        {
            // (Optional) Set OS mouse position from Dear ImGui if requested (rarely used, only when io.ConfigNavMoveSetMousePos is enabled by user)
+            // When multi-viewports are enabled, all Dear ImGui positions are same as OS positions.
            if (io.WantSetMousePos)
-                glfwSetCursorPos(window, (double)io.MousePos.x, (double)io.MousePos.y);
+                glfwSetCursorPos(window, (double)(mouse_pos_prev.x - viewport->Pos.x), (double)(mouse_pos_prev.y - viewport->Pos.y));

            // (Optional) Fallback to provide mouse position when focused (ImGui_ImplGlfw_CursorPosCallback already provides this when hovered or captured)
            if (bd->MouseWindow == nullptr)
            {
                double mouse_x, mouse_y;
                glfwGetCursorPos(window, &mouse_x, &mouse_y);
+                if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+                {
+                    // Single viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
+                    // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
+                    int window_x, window_y;
+                    glfwGetWindowPos(window, &window_x, &window_y);
+                    mouse_x += window_x;
+                    mouse_y += window_y;
+                }
                bd->LastValidMousePos = ImVec2((float)mouse_x, (float)mouse_y);
                io.AddMousePosEvent((float)mouse_x, (float)mouse_y);
            }
        }
+
+        // (Optional) When using multiple viewports: call io.AddMouseViewportEvent() with the viewport the OS mouse cursor is hovering.
+        // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, Dear imGui will ignore this field and infer the information using its flawed heuristic.
+        // - [X] GLFW >= 3.3 backend ON WINDOWS ONLY does correctly ignore viewports with the _NoInputs flag (since we implement hit via our WndProc hook)
+        //       On other platforms we rely on the library fallbacking to its own search when reporting a viewport with _NoInputs flag.
+        // - [!] GLFW <= 3.2 backend CANNOT correctly ignore viewports with the _NoInputs flag, and CANNOT reported Hovered Viewport because of mouse capture.
+        //       Some backend are not able to handle that correctly. If a backend report an hovered viewport that has the _NoInputs flag (e.g. when dragging a window
+        //       for docking, the viewport has the _NoInputs flag in order to allow us to find the viewport under), then Dear ImGui is forced to ignore the value reported
+        //       by the backend, and use its flawed heuristic to guess the viewport behind.
+        // - [X] GLFW backend correctly reports this regardless of another viewport behind focused and dragged from (we need this to find a useful drag and drop target).
+        // FIXME: This is currently only correct on Win32. See what we do below with the WM_NCHITTEST, missing an equivalent for other systems.
+        // See https://github.com/glfw/glfw/issues/1236 if you want to help in making this a GLFW feature.
+#if GLFW_HAS_MOUSE_PASSTHROUGH
+        const bool window_no_input = (viewport->Flags & ImGuiViewportFlags_NoInputs) != 0;
+        glfwSetWindowAttrib(window, GLFW_MOUSE_PASSTHROUGH, window_no_input);
+#endif
+#if GLFW_HAS_MOUSE_PASSTHROUGH || GLFW_HAS_WINDOW_HOVERED
+        if (glfwGetWindowAttrib(window, GLFW_HOVERED))
+            mouse_viewport_id = viewport->ID;
+#else
+        // We cannot use bd->MouseWindow maintained from CursorEnter/Leave callbacks, because it is locked to the window capturing mouse.
+#endif
    }
+
+    if (io.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)
+        io.AddMouseViewportEvent(mouse_viewport_id);
 }

 static void ImGui_ImplGlfw_UpdateMouseCursor()
@@ -753,9 +835,10 @@ static void ImGui_ImplGlfw_UpdateMouseCursor()
        return;

    ImGuiMouseCursor imgui_cursor = ImGui::GetMouseCursor();
-    // (those braces are here to reduce diff with multi-viewports support in 'docking' branch)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
    {
-        GLFWwindow* window = bd->Window;
+        GLFWwindow* window = (GLFWwindow*)platform_io.Viewports[n]->PlatformHandle;
        if (imgui_cursor == ImGuiMouseCursor_None || io.MouseDrawCursor)
        {
            // Hide OS mouse cursor if imgui is drawing it or if it wants no cursor
@@ -824,6 +907,50 @@ static void ImGui_ImplGlfw_UpdateGamepads()
    #undef MAP_ANALOG
 }

+static void ImGui_ImplGlfw_UpdateMonitors()
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    bd->WantUpdateMonitors = false;
+
+    int monitors_count = 0;
+    GLFWmonitor** glfw_monitors = glfwGetMonitors(&monitors_count);
+    if (monitors_count == 0) // Preserve existing monitor list if there are none. Happens on macOS sleeping (#5683)
+        return;
+
+    platform_io.Monitors.resize(0);
+    for (int n = 0; n < monitors_count; n++)
+    {
+        ImGuiPlatformMonitor monitor;
+        int x, y;
+        glfwGetMonitorPos(glfw_monitors[n], &x, &y);
+        const GLFWvidmode* vid_mode = glfwGetVideoMode(glfw_monitors[n]);
+        if (vid_mode == nullptr)
+            continue; // Failed to get Video mode (e.g. Emscripten does not support this function)
+        monitor.MainPos = monitor.WorkPos = ImVec2((float)x, (float)y);
+        monitor.MainSize = monitor.WorkSize = ImVec2((float)vid_mode->width, (float)vid_mode->height);
+#if GLFW_HAS_MONITOR_WORK_AREA
+        int w, h;
+        glfwGetMonitorWorkarea(glfw_monitors[n], &x, &y, &w, &h);
+        if (w > 0 && h > 0) // Workaround a small GLFW issue reporting zero on monitor changes: https://github.com/glfw/glfw/pull/1761
+        {
+            monitor.WorkPos = ImVec2((float)x, (float)y);
+            monitor.WorkSize = ImVec2((float)w, (float)h);
+        }
+#endif
+#if GLFW_HAS_PER_MONITOR_DPI
+        // Warning: the validity of monitor DPI information on Windows depends on the application DPI awareness settings, which generally needs to be set in the manifest or at runtime.
+        float x_scale, y_scale;
+        glfwGetMonitorContentScale(glfw_monitors[n], &x_scale, &y_scale);
+        if (x_scale == 0.0f)
+            continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
+        monitor.DpiScale = x_scale;
+#endif
+        monitor.PlatformHandle = (void*)glfw_monitors[n]; // [...] GLFW doc states: "guaranteed to be valid only until the monitor configuration changes"
+        platform_io.Monitors.push_back(monitor);
+    }
+}
+
 void ImGui_ImplGlfw_NewFrame()
 {
    ImGuiIO& io = ImGui::GetIO();
@@ -838,6 +965,8 @@ void ImGui_ImplGlfw_NewFrame()
    io.DisplaySize = ImVec2((float)w, (float)h);
    if (w > 0 && h > 0)
        io.DisplayFramebufferScale = ImVec2((float)display_w / (float)w, (float)display_h / (float)h);
+    if (bd->WantUpdateMonitors)
+        ImGui_ImplGlfw_UpdateMonitors();

    // Setup time step
    // (Accept glfwGetTime() not returning a monotonically increasing value. Seems to happens on disconnecting peripherals and probably on VMs and Emscripten, see #6491, #6189, #6114, #3644)
@@ -847,6 +976,7 @@ void ImGui_ImplGlfw_NewFrame()
    io.DeltaTime = bd->Time > 0.0 ? (float)(current_time - bd->Time) : (float)(1.0f / 60.0f);
    bd->Time = current_time;

+    bd->MouseIgnoreButtonUp = false;
    ImGui_ImplGlfw_UpdateMouseData();
    ImGui_ImplGlfw_UpdateMouseCursor();

@@ -916,6 +1046,404 @@ void ImGui_ImplGlfw_InstallEmscriptenCallbacks(GLFWwindow* window, const char* c
 }
 #endif // #ifdef EMSCRIPTEN_USE_PORT_CONTRIB_GLFW3

+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplGlfw_ViewportData
+{
+    GLFWwindow* Window;
+    bool        WindowOwned;
+    int         IgnoreWindowPosEventFrame;
+    int         IgnoreWindowSizeEventFrame;
+#ifdef _WIN32
+    WNDPROC     PrevWndProc;
+#endif
+
+    ImGui_ImplGlfw_ViewportData()  { memset(this, 0, sizeof(*this)); IgnoreWindowSizeEventFrame = IgnoreWindowPosEventFrame = -1; }
+    ~ImGui_ImplGlfw_ViewportData() { IM_ASSERT(Window == nullptr); }
+};
+
+static void ImGui_ImplGlfw_WindowCloseCallback(GLFWwindow* window)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+        viewport->PlatformRequestClose = true;
+}
+
+// GLFW may dispatch window pos/size events after calling glfwSetWindowPos()/glfwSetWindowSize().
+// However: depending on the platform the callback may be invoked at different time:
+// - on Windows it appears to be called within the glfwSetWindowPos()/glfwSetWindowSize() call
+// - on Linux it is queued and invoked during glfwPollEvents()
+// Because the event doesn't always fire on glfwSetWindowXXX() we use a frame counter tag to only
+// ignore recent glfwSetWindowXXX() calls.
+static void ImGui_ImplGlfw_WindowPosCallback(GLFWwindow* window, int, int)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+    {
+        if (ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData)
+        {
+            bool ignore_event = (ImGui::GetFrameCount() <= vd->IgnoreWindowPosEventFrame + 1);
+            //data->IgnoreWindowPosEventFrame = -1;
+            if (ignore_event)
+                return;
+        }
+        viewport->PlatformRequestMove = true;
+    }
+}
+
+static void ImGui_ImplGlfw_WindowSizeCallback(GLFWwindow* window, int, int)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+    {
+        if (ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData)
+        {
+            bool ignore_event = (ImGui::GetFrameCount() <= vd->IgnoreWindowSizeEventFrame + 1);
+            //data->IgnoreWindowSizeEventFrame = -1;
+            if (ignore_event)
+                return;
+        }
+        viewport->PlatformRequestResize = true;
+    }
+}
+
+static void ImGui_ImplGlfw_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGui_ImplGlfw_ViewportData* vd = IM_NEW(ImGui_ImplGlfw_ViewportData)();
+    viewport->PlatformUserData = vd;
+
+    // Workaround for Linux: ignore mouse up events corresponding to losing focus of the previously focused window (#7733, #3158, #7922)
+#ifdef __linux__
+    bd->MouseIgnoreButtonUpWaitForFocusLoss = true;
+#endif
+
+    // GLFW 3.2 unfortunately always set focus on glfwCreateWindow() if GLFW_VISIBLE is set, regardless of GLFW_FOCUSED
+    // With GLFW 3.3, the hint GLFW_FOCUS_ON_SHOW fixes this problem
+    glfwWindowHint(GLFW_VISIBLE, false);
+    glfwWindowHint(GLFW_FOCUSED, false);
+#if GLFW_HAS_FOCUS_ON_SHOW
+    glfwWindowHint(GLFW_FOCUS_ON_SHOW, false);
+ #endif
+    glfwWindowHint(GLFW_DECORATED, (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? false : true);
+#if GLFW_HAS_WINDOW_TOPMOST
+    glfwWindowHint(GLFW_FLOATING, (viewport->Flags & ImGuiViewportFlags_TopMost) ? true : false);
+#endif
+    GLFWwindow* share_window = (bd->ClientApi == GlfwClientApi_OpenGL) ? bd->Window : nullptr;
+    vd->Window = glfwCreateWindow((int)viewport->Size.x, (int)viewport->Size.y, "No Title Yet", nullptr, share_window);
+    vd->WindowOwned = true;
+    viewport->PlatformHandle = (void*)vd->Window;
+#ifdef _WIN32
+    viewport->PlatformHandleRaw = glfwGetWin32Window(vd->Window);
+#elif defined(__APPLE__)
+    viewport->PlatformHandleRaw = (void*)glfwGetCocoaWindow(vd->Window);
+#endif
+    glfwSetWindowPos(vd->Window, (int)viewport->Pos.x, (int)viewport->Pos.y);
+
+    // Install GLFW callbacks for secondary viewports
+    glfwSetWindowFocusCallback(vd->Window, ImGui_ImplGlfw_WindowFocusCallback);
+    glfwSetCursorEnterCallback(vd->Window, ImGui_ImplGlfw_CursorEnterCallback);
+    glfwSetCursorPosCallback(vd->Window, ImGui_ImplGlfw_CursorPosCallback);
+    glfwSetMouseButtonCallback(vd->Window, ImGui_ImplGlfw_MouseButtonCallback);
+    glfwSetScrollCallback(vd->Window, ImGui_ImplGlfw_ScrollCallback);
+    glfwSetKeyCallback(vd->Window, ImGui_ImplGlfw_KeyCallback);
+    glfwSetCharCallback(vd->Window, ImGui_ImplGlfw_CharCallback);
+    glfwSetWindowCloseCallback(vd->Window, ImGui_ImplGlfw_WindowCloseCallback);
+    glfwSetWindowPosCallback(vd->Window, ImGui_ImplGlfw_WindowPosCallback);
+    glfwSetWindowSizeCallback(vd->Window, ImGui_ImplGlfw_WindowSizeCallback);
+    if (bd->ClientApi == GlfwClientApi_OpenGL)
+    {
+        glfwMakeContextCurrent(vd->Window);
+        glfwSwapInterval(0);
+    }
+}
+
+static void ImGui_ImplGlfw_DestroyWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    if (ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData)
+    {
+        if (vd->WindowOwned)
+        {
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED && defined(_WIN32)
+            HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+            ::RemovePropA(hwnd, "IMGUI_VIEWPORT");
+#endif
+
+            // Release any keys that were pressed in the window being destroyed and are still held down,
+            // because we will not receive any release events after window is destroyed.
+            for (int i = 0; i < IM_ARRAYSIZE(bd->KeyOwnerWindows); i++)
+                if (bd->KeyOwnerWindows[i] == vd->Window)
+                    ImGui_ImplGlfw_KeyCallback(vd->Window, i, 0, GLFW_RELEASE, 0); // Later params are only used for main viewport, on which this function is never called.
+
+            glfwDestroyWindow(vd->Window);
+        }
+        vd->Window = nullptr;
+        IM_DELETE(vd);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = nullptr;
+}
+
+static void ImGui_ImplGlfw_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+
+#if defined(_WIN32)
+    // GLFW hack: Hide icon from task bar
+    HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+    if (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon)
+    {
+        LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
+        ex_style &= ~WS_EX_APPWINDOW;
+        ex_style |= WS_EX_TOOLWINDOW;
+        ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
+    }
+
+    // GLFW hack: install hook for WM_NCHITTEST message handler
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED && defined(_WIN32)
+    ::SetPropA(hwnd, "IMGUI_VIEWPORT", viewport);
+    vd->PrevWndProc = (WNDPROC)::GetWindowLongPtrW(hwnd, GWLP_WNDPROC);
+    ::SetWindowLongPtrW(hwnd, GWLP_WNDPROC, (LONG_PTR)ImGui_ImplGlfw_WndProc);
+#endif
+
+#if !GLFW_HAS_FOCUS_ON_SHOW
+    // GLFW hack: GLFW 3.2 has a bug where glfwShowWindow() also activates/focus the window.
+    // The fix was pushed to GLFW repository on 2018/01/09 and should be included in GLFW 3.3 via a GLFW_FOCUS_ON_SHOW window attribute.
+    // See https://github.com/glfw/glfw/issues/1189
+    // FIXME-VIEWPORT: Implement same work-around for Linux/OSX in the meanwhile.
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+    {
+        ::ShowWindow(hwnd, SW_SHOWNA);
+        return;
+    }
+#endif
+#endif
+
+    glfwShowWindow(vd->Window);
+}
+
+static ImVec2 ImGui_ImplGlfw_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    int x = 0, y = 0;
+    glfwGetWindowPos(vd->Window, &x, &y);
+    return ImVec2((float)x, (float)y);
+}
+
+static void ImGui_ImplGlfw_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    vd->IgnoreWindowPosEventFrame = ImGui::GetFrameCount();
+    glfwSetWindowPos(vd->Window, (int)pos.x, (int)pos.y);
+}
+
+static ImVec2 ImGui_ImplGlfw_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    int w = 0, h = 0;
+    glfwGetWindowSize(vd->Window, &w, &h);
+    return ImVec2((float)w, (float)h);
+}
+
+static void ImGui_ImplGlfw_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+#if __APPLE__ && !GLFW_HAS_OSX_WINDOW_POS_FIX
+    // Native OS windows are positioned from the bottom-left corner on macOS, whereas on other platforms they are
+    // positioned from the upper-left corner. GLFW makes an effort to convert macOS style coordinates, however it
+    // doesn't handle it when changing size. We are manually moving the window in order for changes of size to be based
+    // on the upper-left corner.
+    int x, y, width, height;
+    glfwGetWindowPos(vd->Window, &x, &y);
+    glfwGetWindowSize(vd->Window, &width, &height);
+    glfwSetWindowPos(vd->Window, x, y - height + size.y);
+#endif
+    vd->IgnoreWindowSizeEventFrame = ImGui::GetFrameCount();
+    glfwSetWindowSize(vd->Window, (int)size.x, (int)size.y);
+}
+
+static void ImGui_ImplGlfw_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    glfwSetWindowTitle(vd->Window, title);
+}
+
+static void ImGui_ImplGlfw_SetWindowFocus(ImGuiViewport* viewport)
+{
+#if GLFW_HAS_FOCUS_WINDOW
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    glfwFocusWindow(vd->Window);
+#else
+    // FIXME: What are the effect of not having this function? At the moment imgui doesn't actually call SetWindowFocus - we set that up ahead, will answer that question later.
+    (void)viewport;
+#endif
+}
+
+static bool ImGui_ImplGlfw_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    return glfwGetWindowAttrib(vd->Window, GLFW_FOCUSED) != 0;
+}
+
+static bool ImGui_ImplGlfw_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    return glfwGetWindowAttrib(vd->Window, GLFW_ICONIFIED) != 0;
+}
+
+#if GLFW_HAS_WINDOW_ALPHA
+static void ImGui_ImplGlfw_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    glfwSetWindowOpacity(vd->Window, alpha);
+}
+#endif
+
+static void ImGui_ImplGlfw_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    if (bd->ClientApi == GlfwClientApi_OpenGL)
+        glfwMakeContextCurrent(vd->Window);
+}
+
+static void ImGui_ImplGlfw_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    if (bd->ClientApi == GlfwClientApi_OpenGL)
+    {
+        glfwMakeContextCurrent(vd->Window);
+        glfwSwapBuffers(vd->Window);
+    }
+}
+
+//--------------------------------------------------------------------------------------------------------
+// Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
+//--------------------------------------------------------------------------------------------------------
+
+// Avoid including <vulkan.h> so we can build without it
+#if GLFW_HAS_VULKAN
+#ifndef VULKAN_H_
+#define VK_DEFINE_HANDLE(object) typedef struct object##_T* object;
+#if defined(__LP64__) || defined(_WIN64) || defined(__x86_64__) || defined(_M_X64) || defined(__ia64) || defined (_M_IA64) || defined(__aarch64__) || defined(__powerpc64__)
+#define VK_DEFINE_NON_DISPATCHABLE_HANDLE(object) typedef struct object##_T *object;
+#else
+#define VK_DEFINE_NON_DISPATCHABLE_HANDLE(object) typedef uint64_t object;
+#endif
+VK_DEFINE_HANDLE(VkInstance)
+VK_DEFINE_NON_DISPATCHABLE_HANDLE(VkSurfaceKHR)
+struct VkAllocationCallbacks;
+enum VkResult { VK_RESULT_MAX_ENUM = 0x7FFFFFFF };
+#endif // VULKAN_H_
+extern "C" { extern GLFWAPI VkResult glfwCreateWindowSurface(VkInstance instance, GLFWwindow* window, const VkAllocationCallbacks* allocator, VkSurfaceKHR* surface); }
+static int ImGui_ImplGlfw_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    IM_UNUSED(bd);
+    IM_ASSERT(bd->ClientApi == GlfwClientApi_Vulkan);
+    VkResult err = glfwCreateWindowSurface((VkInstance)vk_instance, vd->Window, (const VkAllocationCallbacks*)vk_allocator, (VkSurfaceKHR*)out_vk_surface);
+    return (int)err;
+}
+#endif // GLFW_HAS_VULKAN
+
+static void ImGui_ImplGlfw_InitMultiViewportSupport()
+{
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplGlfw_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplGlfw_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplGlfw_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplGlfw_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplGlfw_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplGlfw_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplGlfw_GetWindowSize;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplGlfw_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplGlfw_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplGlfw_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplGlfw_SetWindowTitle;
+    platform_io.Platform_RenderWindow = ImGui_ImplGlfw_RenderWindow;
+    platform_io.Platform_SwapBuffers = ImGui_ImplGlfw_SwapBuffers;
+#if GLFW_HAS_WINDOW_ALPHA
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplGlfw_SetWindowAlpha;
+#endif
+#if GLFW_HAS_VULKAN
+    platform_io.Platform_CreateVkSurface = ImGui_ImplGlfw_CreateVkSurface;
+#endif
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplGlfw_ViewportData* vd = IM_NEW(ImGui_ImplGlfw_ViewportData)();
+    vd->Window = bd->Window;
+    vd->WindowOwned = false;
+    main_viewport->PlatformUserData = vd;
+    main_viewport->PlatformHandle = (void*)bd->Window;
+}
+
+static void ImGui_ImplGlfw_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
+//-----------------------------------------------------------------------------
+
+// WndProc hook (declared here because we will need access to ImGui_ImplGlfw_ViewportData)
+#ifdef _WIN32
+static ImGuiMouseSource GetMouseSourceFromMessageExtraInfo()
+{
+    LPARAM extra_info = ::GetMessageExtraInfo();
+    if ((extra_info & 0xFFFFFF80) == 0xFF515700)
+        return ImGuiMouseSource_Pen;
+    if ((extra_info & 0xFFFFFF80) == 0xFF515780)
+        return ImGuiMouseSource_TouchScreen;
+    return ImGuiMouseSource_Mouse;
+}
+static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    WNDPROC prev_wndproc = bd->PrevWndProc;
+    ImGuiViewport* viewport = (ImGuiViewport*)::GetPropA(hWnd, "IMGUI_VIEWPORT");
+    if (viewport != NULL)
+        if (ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData)
+            prev_wndproc = vd->PrevWndProc;
+
+    switch (msg)
+    {
+        // GLFW doesn't allow to distinguish Mouse vs TouchScreen vs Pen.
+        // Add support for Win32 (based on imgui_impl_win32), because we rely on _TouchScreen info to trickle inputs differently.
+    case WM_MOUSEMOVE: case WM_NCMOUSEMOVE:
+    case WM_LBUTTONDOWN: case WM_LBUTTONDBLCLK: case WM_LBUTTONUP:
+    case WM_RBUTTONDOWN: case WM_RBUTTONDBLCLK: case WM_RBUTTONUP:
+    case WM_MBUTTONDOWN: case WM_MBUTTONDBLCLK: case WM_MBUTTONUP:
+    case WM_XBUTTONDOWN: case WM_XBUTTONDBLCLK: case WM_XBUTTONUP:
+        ImGui::GetIO().AddMouseSourceEvent(GetMouseSourceFromMessageExtraInfo());
+        break;
+
+        // We have submitted https://github.com/glfw/glfw/pull/1568 to allow GLFW to support "transparent inputs".
+        // In the meanwhile we implement custom per-platform workarounds here (FIXME-VIEWPORT: Implement same work-around for Linux/OSX!)
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED
+    case WM_NCHITTEST:
+    {
+        // Let mouse pass-through the window. This will allow the backend to call io.AddMouseViewportEvent() properly (which is OPTIONAL).
+        // The ImGuiViewportFlags_NoInputs flag is set while dragging a viewport, as want to detect the window behind the one we are dragging.
+        // If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
+        // your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
+        if (viewport && (viewport->Flags & ImGuiViewportFlags_NoInputs))
+            return HTTRANSPARENT;
+        break;
+    }
+#endif
+    }
+    return ::CallWindowProcW(prev_wndproc, hWnd, msg, wParam, lParam);
+}
+#endif // #ifdef _WIN32
+
 //-----------------------------------------------------------------------------

 #if defined(__clang__)
@@ -1,6 +1,7 @@
 // dear imgui: Platform Backend for GLFW
 // This needs to be used along with a Renderer (e.g. OpenGL3, Vulkan, WebGPU..)
 // (Info: GLFW is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
+// (Requires: GLFW 3.1+. Prefer GLFW 3.3+ for full feature support.)

 // Implemented features:
 //  [X] Platform: Clipboard support.
@@ -8,6 +9,9 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy GLFW_KEY_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
 //  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange' (note: the resizing cursors requires GLFW 3.4+).
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+// Issues:
+//  [ ] Platform: Multi-viewport: ParentViewportID not honored, and so io.ConfigViewportsNoDefaultParent has no effect (minor).

 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -2,9 +2,10 @@
 // This needs to be used along with a Platform Backend (e.g. GLFW, SDL, Win32, custom..)

 // Implemented features:
-//  [!] Renderer: User texture binding. Use 'VkDescriptorSet' as ImTextureID. Read the FAQ about ImTextureID! See https://github.com/ocornut/imgui/pull/914 for discussions.
+//  [x] Renderer: User texture binding. Use 'VkDescriptorSet' as ImTextureID. Read the FAQ about ImTextureID! See https://github.com/ocornut/imgui/pull/914 for discussions.
 //  [X] Renderer: Large meshes support (64k+ vertices) with 16-bit indices.
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+//  [x] Renderer: Multi-viewport / platform windows. With issues (flickering when creating a new viewport).

 // The aim of imgui_impl_vulkan.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
@@ -26,6 +27,7 @@

 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2024-10-07: Vulkan: Changed default texture sampler to Clamp instead of Repeat/Wrap.
 //  2024-10-07: Vulkan: Expose selected render state in ImGui_ImplVulkan_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
 //  2024-10-07: Vulkan: Compiling with '#define ImTextureID=ImU64' is unnecessary now that dear imgui defaults ImTextureID to u64 instead of void*.
@@ -100,6 +102,7 @@ void ImGui_ImplVulkan_DestroyFrameRenderBuffers(VkDevice device, ImGui_ImplVulka
 void ImGui_ImplVulkan_DestroyWindowRenderBuffers(VkDevice device, ImGui_ImplVulkan_WindowRenderBuffers* buffers, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_DestroyFrame(VkDevice device, ImGui_ImplVulkanH_Frame* fd, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_DestroyFrameSemaphores(VkDevice device, ImGui_ImplVulkanH_FrameSemaphores* fsd, const VkAllocationCallbacks* allocator);
+void ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(VkDevice device, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count);
 void ImGui_ImplVulkanH_CreateWindowCommandBuffers(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator);

@@ -116,15 +119,18 @@ static bool g_FunctionsLoaded = true;
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkAllocateCommandBuffers) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkAllocateDescriptorSets) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkAllocateMemory) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkAcquireNextImageKHR) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkBeginCommandBuffer) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkBindBufferMemory) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkBindImageMemory) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBeginRenderPass) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBindDescriptorSets) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBindIndexBuffer) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBindPipeline) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBindVertexBuffers) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdCopyBufferToImage) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdDrawIndexed) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdEndRenderPass) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdPipelineBarrier) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdPushConstants) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdSetScissor) \
@@ -170,13 +176,17 @@ static bool g_FunctionsLoaded = true;
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetPhysicalDeviceSurfaceCapabilitiesKHR) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetPhysicalDeviceSurfaceFormatsKHR) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetPhysicalDeviceSurfacePresentModesKHR) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetPhysicalDeviceSurfaceSupportKHR) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetSwapchainImagesKHR) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkMapMemory) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkQueuePresentKHR) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkQueueSubmit) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkQueueWaitIdle) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkResetCommandPool) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkResetFences) \
    IMGUI_VULKAN_FUNC_MAP_MACRO(vkUnmapMemory) \
-    IMGUI_VULKAN_FUNC_MAP_MACRO(vkUpdateDescriptorSets)
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkUpdateDescriptorSets) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkWaitForFences)

 // Define function pointers
 #define IMGUI_VULKAN_FUNC_DEF(func) static PFN_##func func;
@@ -210,6 +220,19 @@ struct ImGui_ImplVulkan_WindowRenderBuffers
    ImGui_ImplVulkan_FrameRenderBuffers* FrameRenderBuffers;
 };

+// For multi-viewport support:
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplVulkan_ViewportData
+{
+    ImGui_ImplVulkanH_Window                Window;                 // Used by secondary viewports only
+    ImGui_ImplVulkan_WindowRenderBuffers    RenderBuffers;          // Used by all viewports
+    bool                                    WindowOwned;
+    bool                                    SwapChainNeedRebuild;   // Flag when viewport swapchain resized in the middle of processing a frame
+
+    ImGui_ImplVulkan_ViewportData()         { WindowOwned = SwapChainNeedRebuild = false; memset(&RenderBuffers, 0, sizeof(RenderBuffers)); }
+    ~ImGui_ImplVulkan_ViewportData()        { }
+};
+
 // Vulkan data
 struct ImGui_ImplVulkan_Data
 {
@@ -218,7 +241,8 @@ struct ImGui_ImplVulkan_Data
    VkPipelineCreateFlags       PipelineCreateFlags;
    VkDescriptorSetLayout       DescriptorSetLayout;
    VkPipelineLayout            PipelineLayout;
-    VkPipeline                  Pipeline;
+    VkPipeline                  Pipeline;               // pipeline for main render pass (created by app)
+    VkPipeline                  PipelineForViewports;   // pipeline for secondary viewports (created by backend)
    VkShaderModule              ShaderModuleVert;
    VkShaderModule              ShaderModuleFrag;

@@ -245,6 +269,10 @@ struct ImGui_ImplVulkan_Data
 // SHADERS
 //-----------------------------------------------------------------------------

+// Forward Declarations
+static void ImGui_ImplVulkan_InitMultiViewportSupport();
+static void ImGui_ImplVulkan_ShutdownMultiViewportSupport();
+
 // backends/vulkan/glsl_shader.vert, compiled with:
 // # glslangValidator -V -x -o glsl_shader.vert.u32 glsl_shader.vert
 /*
@@ -482,8 +510,10 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
    if (pipeline == VK_NULL_HANDLE)
        pipeline = bd->Pipeline;

-    // Allocate array to store enough vertex/index buffers
-    ImGui_ImplVulkan_WindowRenderBuffers* wrb = &bd->MainWindowRenderBuffers;
+    // Allocate array to store enough vertex/index buffers. Each unique viewport gets its own storage.
+    ImGui_ImplVulkan_ViewportData* viewport_renderer_data = (ImGui_ImplVulkan_ViewportData*)draw_data->OwnerViewport->RendererUserData;
+    IM_ASSERT(viewport_renderer_data != nullptr);
+    ImGui_ImplVulkan_WindowRenderBuffers* wrb = &viewport_renderer_data->RenderBuffers;
    if (wrb->FrameRenderBuffers == nullptr)
    {
        wrb->Index = 0;
@@ -1037,7 +1067,7 @@ void    ImGui_ImplVulkan_DestroyDeviceObjects()
 {
    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
-    ImGui_ImplVulkan_DestroyWindowRenderBuffers(v->Device, &bd->MainWindowRenderBuffers, v->Allocator);
+    ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(v->Device, v->Allocator);
    ImGui_ImplVulkan_DestroyFontsTexture();

    if (bd->FontCommandBuffer)    { vkFreeCommandBuffers(v->Device, bd->FontCommandPool, 1, &bd->FontCommandBuffer); bd->FontCommandBuffer = VK_NULL_HANDLE; }
@@ -1048,6 +1078,7 @@ void    ImGui_ImplVulkan_DestroyDeviceObjects()
    if (bd->DescriptorSetLayout)  { vkDestroyDescriptorSetLayout(v->Device, bd->DescriptorSetLayout, v->Allocator); bd->DescriptorSetLayout = VK_NULL_HANDLE; }
    if (bd->PipelineLayout)       { vkDestroyPipelineLayout(v->Device, bd->PipelineLayout, v->Allocator); bd->PipelineLayout = VK_NULL_HANDLE; }
    if (bd->Pipeline)             { vkDestroyPipeline(v->Device, bd->Pipeline, v->Allocator); bd->Pipeline = VK_NULL_HANDLE; }
+    if (bd->PipelineForViewports) { vkDestroyPipeline(v->Device, bd->PipelineForViewports, v->Allocator); bd->PipelineForViewports = VK_NULL_HANDLE; }
 }

 bool    ImGui_ImplVulkan_LoadFunctions(PFN_vkVoidFunction(*loader_func)(const char* function_name, void* user_data), void* user_data)
@@ -1105,6 +1136,7 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info)
    io.BackendRendererUserData = (void*)bd;
    io.BackendRendererName = "imgui_impl_vulkan";
    io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)

    IM_ASSERT(info->Instance != VK_NULL_HANDLE);
    IM_ASSERT(info->PhysicalDevice != VK_NULL_HANDLE);
@@ -1120,6 +1152,12 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info)

    ImGui_ImplVulkan_CreateDeviceObjects();

+    // Our render function expect RendererUserData to be storing the window render buffer we need (for the main viewport we won't use ->Window)
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    main_viewport->RendererUserData = IM_NEW(ImGui_ImplVulkan_ViewportData)();
+
+    ImGui_ImplVulkan_InitMultiViewportSupport();
+
    return true;
 }

@@ -1129,10 +1167,21 @@ void ImGui_ImplVulkan_Shutdown()
    IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
    ImGuiIO& io = ImGui::GetIO();

+    // First destroy objects in all viewports
    ImGui_ImplVulkan_DestroyDeviceObjects();
+
+    // Manually delete main viewport render data in-case we haven't initialized for viewports
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    if (ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)main_viewport->RendererUserData)
+        IM_DELETE(vd);
+    main_viewport->RendererUserData = nullptr;
+
+    // Clean up windows
+    ImGui_ImplVulkan_ShutdownMultiViewportSupport();
+
    io.BackendRendererName = nullptr;
    io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~ImGuiBackendFlags_RendererHasVtxOffset;
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasViewports);
    IM_DELETE(bd);
 }

@@ -1152,10 +1201,12 @@ void ImGui_ImplVulkan_SetMinImageCount(uint32_t min_image_count)
    if (bd->VulkanInitInfo.MinImageCount == min_image_count)
        return;

+    IM_ASSERT(0); // FIXME-VIEWPORT: Unsupported. Need to recreate all swap chains!
    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
    VkResult err = vkDeviceWaitIdle(v->Device);
    check_vk_result(err);
-    ImGui_ImplVulkan_DestroyWindowRenderBuffers(v->Device, &bd->MainWindowRenderBuffers, v->Allocator);
+    ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(v->Device, v->Allocator);
+
    bd->VulkanInitInfo.MinImageCount = min_image_count;
 }

@@ -1390,8 +1441,6 @@ void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, V
    wd->ImageCount = 0;
    if (wd->RenderPass)
        vkDestroyRenderPass(device, wd->RenderPass, allocator);
-    if (wd->Pipeline)
-        vkDestroyPipeline(device, wd->Pipeline, allocator);

    // If min image count was not specified, request different count of images dependent on selected present mode
    if (min_image_count == 0)
@@ -1544,6 +1593,7 @@ void ImGui_ImplVulkanH_CreateOrResizeWindow(VkInstance instance, VkPhysicalDevic
    IM_ASSERT(g_FunctionsLoaded && "Need to call ImGui_ImplVulkan_LoadFunctions() if IMGUI_IMPL_VULKAN_NO_PROTOTYPES or VK_NO_PROTOTYPES are set!");
    (void)instance;
    ImGui_ImplVulkanH_CreateWindowSwapChain(physical_device, device, wd, allocator, width, height, min_image_count);
+    //ImGui_ImplVulkan_CreatePipeline(device, allocator, VK_NULL_HANDLE, wd->RenderPass, VK_SAMPLE_COUNT_1_BIT, &wd->Pipeline, g_VulkanInitInfo.Subpass);
    ImGui_ImplVulkanH_CreateWindowCommandBuffers(physical_device, device, wd, queue_family, allocator);
 }

@@ -1560,7 +1610,6 @@ void ImGui_ImplVulkanH_DestroyWindow(VkInstance instance, VkDevice device, ImGui
    IM_FREE(wd->FrameSemaphores);
    wd->Frames = nullptr;
    wd->FrameSemaphores = nullptr;
-    vkDestroyPipeline(device, wd->Pipeline, allocator);
    vkDestroyRenderPass(device, wd->RenderPass, allocator);
    vkDestroySwapchainKHR(device, wd->Swapchain, allocator);
    vkDestroySurfaceKHR(instance, wd->Surface, allocator);
@@ -1588,6 +1637,297 @@ void ImGui_ImplVulkanH_DestroyFrameSemaphores(VkDevice device, ImGui_ImplVulkanH
    fsd->ImageAcquiredSemaphore = fsd->RenderCompleteSemaphore = VK_NULL_HANDLE;
 }

+void ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(VkDevice device, const VkAllocationCallbacks* allocator)
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
+        if (ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)platform_io.Viewports[n]->RendererUserData)
+            ImGui_ImplVulkan_DestroyWindowRenderBuffers(device, &vd->RenderBuffers, allocator);
+}
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplVulkan_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_ViewportData* vd = IM_NEW(ImGui_ImplVulkan_ViewportData)();
+    viewport->RendererUserData = vd;
+    ImGui_ImplVulkanH_Window* wd = &vd->Window;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+
+    // Create surface
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    VkResult err = (VkResult)platform_io.Platform_CreateVkSurface(viewport, (ImU64)v->Instance, (const void*)v->Allocator, (ImU64*)&wd->Surface);
+    check_vk_result(err);
+
+    // Check for WSI support
+    VkBool32 res;
+    vkGetPhysicalDeviceSurfaceSupportKHR(v->PhysicalDevice, v->QueueFamily, wd->Surface, &res);
+    if (res != VK_TRUE)
+    {
+        IM_ASSERT(0); // Error: no WSI support on physical device
+        return;
+    }
+
+    // Select Surface Format
+    ImVector<VkFormat> requestSurfaceImageFormats;
+#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+    for (uint32_t n = 0; n < v->PipelineRenderingCreateInfo.colorAttachmentCount; n++)
+        requestSurfaceImageFormats.push_back(v->PipelineRenderingCreateInfo.pColorAttachmentFormats[n]);
+#endif
+    const VkFormat defaultFormats[] = { VK_FORMAT_B8G8R8A8_UNORM, VK_FORMAT_R8G8B8A8_UNORM, VK_FORMAT_B8G8R8_UNORM, VK_FORMAT_R8G8B8_UNORM };
+    for (VkFormat format : defaultFormats)
+        requestSurfaceImageFormats.push_back(format);
+
+    const VkColorSpaceKHR requestSurfaceColorSpace = VK_COLORSPACE_SRGB_NONLINEAR_KHR;
+    wd->SurfaceFormat = ImGui_ImplVulkanH_SelectSurfaceFormat(v->PhysicalDevice, wd->Surface, requestSurfaceImageFormats.Data, (size_t)requestSurfaceImageFormats.Size, requestSurfaceColorSpace);
+
+    // Select Present Mode
+    // FIXME-VULKAN: Even thought mailbox seems to get us maximum framerate with a single window, it halves framerate with a second window etc. (w/ Nvidia and SDK 1.82.1)
+    VkPresentModeKHR present_modes[] = { VK_PRESENT_MODE_MAILBOX_KHR, VK_PRESENT_MODE_IMMEDIATE_KHR, VK_PRESENT_MODE_FIFO_KHR };
+    wd->PresentMode = ImGui_ImplVulkanH_SelectPresentMode(v->PhysicalDevice, wd->Surface, &present_modes[0], IM_ARRAYSIZE(present_modes));
+    //printf("[vulkan] Secondary window selected PresentMode = %d\n", wd->PresentMode);
+
+    // Create SwapChain, RenderPass, Framebuffer, etc.
+    wd->ClearEnable = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? false : true;
+    wd->UseDynamicRendering = v->UseDynamicRendering;
+    ImGui_ImplVulkanH_CreateOrResizeWindow(v->Instance, v->PhysicalDevice, v->Device, wd, v->QueueFamily, v->Allocator, (int)viewport->Size.x, (int)viewport->Size.y, v->MinImageCount);
+    vd->WindowOwned = true;
+
+    // Create pipeline (shared by all secondary viewports)
+    if (bd->PipelineForViewports == VK_NULL_HANDLE)
+        ImGui_ImplVulkan_CreatePipeline(v->Device, v->Allocator, VK_NULL_HANDLE, wd->RenderPass, VK_SAMPLE_COUNT_1_BIT, &bd->PipelineForViewports, 0);
+}
+
+static void ImGui_ImplVulkan_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == 0 since we didn't create the data for it.
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    if (ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData)
+    {
+        ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+        if (vd->WindowOwned)
+            ImGui_ImplVulkanH_DestroyWindow(v->Instance, v->Device, &vd->Window, v->Allocator);
+        ImGui_ImplVulkan_DestroyWindowRenderBuffers(v->Device, &vd->RenderBuffers, v->Allocator);
+        IM_DELETE(vd);
+    }
+    viewport->RendererUserData = nullptr;
+}
+
+static void ImGui_ImplVulkan_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData;
+    if (vd == nullptr) // This is nullptr for the main viewport (which is left to the user/app to handle)
+        return;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+    vd->Window.ClearEnable = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? false : true;
+    ImGui_ImplVulkanH_CreateOrResizeWindow(v->Instance, v->PhysicalDevice, v->Device, &vd->Window, v->QueueFamily, v->Allocator, (int)size.x, (int)size.y, v->MinImageCount);
+}
+
+static void ImGui_ImplVulkan_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData;
+    ImGui_ImplVulkanH_Window* wd = &vd->Window;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+    VkResult err;
+
+    if (vd->SwapChainNeedRebuild)
+    {
+        ImGui_ImplVulkanH_CreateOrResizeWindow(v->Instance, v->PhysicalDevice, v->Device, wd, v->QueueFamily, v->Allocator, (int)viewport->Size.x, (int)viewport->Size.y, v->MinImageCount);
+        vd->SwapChainNeedRebuild = false;
+    }
+
+    ImGui_ImplVulkanH_Frame* fd = &wd->Frames[wd->FrameIndex];
+    ImGui_ImplVulkanH_FrameSemaphores* fsd = &wd->FrameSemaphores[wd->SemaphoreIndex];
+    {
+        {
+            err = vkAcquireNextImageKHR(v->Device, wd->Swapchain, UINT64_MAX, fsd->ImageAcquiredSemaphore, VK_NULL_HANDLE, &wd->FrameIndex);
+            if (err == VK_ERROR_OUT_OF_DATE_KHR)
+            {
+                // Since we are not going to swap this frame anyway, it's ok that recreation happens on next frame.
+                vd->SwapChainNeedRebuild = true;
+                return;
+            }
+            check_vk_result(err);
+            fd = &wd->Frames[wd->FrameIndex];
+        }
+        for (;;)
+        {
+            err = vkWaitForFences(v->Device, 1, &fd->Fence, VK_TRUE, 100);
+            if (err == VK_SUCCESS) break;
+            if (err == VK_TIMEOUT) continue;
+            check_vk_result(err);
+        }
+        {
+            err = vkResetCommandPool(v->Device, fd->CommandPool, 0);
+            check_vk_result(err);
+            VkCommandBufferBeginInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
+            info.flags |= VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+            err = vkBeginCommandBuffer(fd->CommandBuffer, &info);
+            check_vk_result(err);
+        }
+        {
+            ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+            memcpy(&wd->ClearValue.color.float32[0], &clear_color, 4 * sizeof(float));
+        }
+#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+        if (v->UseDynamicRendering)
+        {
+            // Transition swapchain image to a layout suitable for drawing.
+            VkImageMemoryBarrier barrier = {};
+            barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
+            barrier.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+            barrier.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+            barrier.newLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+            barrier.image = fd->Backbuffer;
+            barrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
+            barrier.subresourceRange.levelCount = 1;
+            barrier.subresourceRange.layerCount = 1;
+            vkCmdPipelineBarrier(fd->CommandBuffer, VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT, 0, 0, nullptr, 0, nullptr, 1, &barrier);
+
+            VkRenderingAttachmentInfo attachmentInfo = {};
+            attachmentInfo.sType = VK_STRUCTURE_TYPE_RENDERING_ATTACHMENT_INFO_KHR;
+            attachmentInfo.imageView = fd->BackbufferView;
+            attachmentInfo.imageLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+            attachmentInfo.resolveMode = VK_RESOLVE_MODE_NONE;
+            attachmentInfo.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+            attachmentInfo.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+            attachmentInfo.clearValue = wd->ClearValue;
+
+            VkRenderingInfo renderingInfo = {};
+            renderingInfo.sType = VK_STRUCTURE_TYPE_RENDERING_INFO_KHR;
+            renderingInfo.renderArea.extent.width = wd->Width;
+            renderingInfo.renderArea.extent.height = wd->Height;
+            renderingInfo.layerCount = 1;
+            renderingInfo.viewMask = 0;
+            renderingInfo.colorAttachmentCount = 1;
+            renderingInfo.pColorAttachments = &attachmentInfo;
+
+            ImGuiImplVulkanFuncs_vkCmdBeginRenderingKHR(fd->CommandBuffer, &renderingInfo);
+        }
+        else
+#endif
+        {
+            VkRenderPassBeginInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
+            info.renderPass = wd->RenderPass;
+            info.framebuffer = fd->Framebuffer;
+            info.renderArea.extent.width = wd->Width;
+            info.renderArea.extent.height = wd->Height;
+            info.clearValueCount = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? 0 : 1;
+            info.pClearValues = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? nullptr : &wd->ClearValue;
+            vkCmdBeginRenderPass(fd->CommandBuffer, &info, VK_SUBPASS_CONTENTS_INLINE);
+        }
+    }
+
+    ImGui_ImplVulkan_RenderDrawData(viewport->DrawData, fd->CommandBuffer, bd->PipelineForViewports);
+
+    {
+#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+        if (v->UseDynamicRendering)
+        {
+            ImGuiImplVulkanFuncs_vkCmdEndRenderingKHR(fd->CommandBuffer);
+
+            // Transition image to a layout suitable for presentation
+            VkImageMemoryBarrier barrier = {};
+            barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
+            barrier.srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+            barrier.oldLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+            barrier.newLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;
+            barrier.image = fd->Backbuffer;
+            barrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
+            barrier.subresourceRange.levelCount = 1;
+            barrier.subresourceRange.layerCount = 1;
+            vkCmdPipelineBarrier(fd->CommandBuffer, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, 0, 0, nullptr, 0, nullptr, 1, &barrier);
+        }
+        else
+#endif
+        {
+            vkCmdEndRenderPass(fd->CommandBuffer);
+        }
+        {
+            VkPipelineStageFlags wait_stage = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+            VkSubmitInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
+            info.waitSemaphoreCount = 1;
+            info.pWaitSemaphores = &fsd->ImageAcquiredSemaphore;
+            info.pWaitDstStageMask = &wait_stage;
+            info.commandBufferCount = 1;
+            info.pCommandBuffers = &fd->CommandBuffer;
+            info.signalSemaphoreCount = 1;
+            info.pSignalSemaphores = &fsd->RenderCompleteSemaphore;
+
+            err = vkEndCommandBuffer(fd->CommandBuffer);
+            check_vk_result(err);
+            err = vkResetFences(v->Device, 1, &fd->Fence);
+            check_vk_result(err);
+            err = vkQueueSubmit(v->Queue, 1, &info, fd->Fence);
+            check_vk_result(err);
+        }
+    }
+}
+
+static void ImGui_ImplVulkan_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData;
+    ImGui_ImplVulkanH_Window* wd = &vd->Window;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+
+    if (vd->SwapChainNeedRebuild) // Frame data became invalid in the middle of rendering
+        return;
+
+    VkResult err;
+    uint32_t present_index = wd->FrameIndex;
+
+    ImGui_ImplVulkanH_FrameSemaphores* fsd = &wd->FrameSemaphores[wd->SemaphoreIndex];
+    VkPresentInfoKHR info = {};
+    info.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
+    info.waitSemaphoreCount = 1;
+    info.pWaitSemaphores = &fsd->RenderCompleteSemaphore;
+    info.swapchainCount = 1;
+    info.pSwapchains = &wd->Swapchain;
+    info.pImageIndices = &present_index;
+    err = vkQueuePresentKHR(v->Queue, &info);
+    if (err == VK_ERROR_OUT_OF_DATE_KHR || err == VK_SUBOPTIMAL_KHR)
+    {
+        vd->SwapChainNeedRebuild = true;
+        if (err == VK_ERROR_OUT_OF_DATE_KHR)
+            return;
+    }
+    else
+    {
+        check_vk_result(err);
+    }
+
+    wd->FrameIndex = (wd->FrameIndex + 1) % wd->ImageCount;             // This is for the next vkWaitForFences()
+    wd->SemaphoreIndex = (wd->SemaphoreIndex + 1) % wd->SemaphoreCount; // Now we can use the next set of semaphores
+}
+
+void ImGui_ImplVulkan_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        IM_ASSERT(platform_io.Platform_CreateVkSurface != nullptr && "Platform needs to setup the CreateVkSurface handler.");
+    platform_io.Renderer_CreateWindow = ImGui_ImplVulkan_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplVulkan_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplVulkan_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplVulkan_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplVulkan_SwapBuffers;
+}
+
+void ImGui_ImplVulkan_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------

 #endif // #ifndef IMGUI_DISABLE
@@ -2,9 +2,10 @@
 // This needs to be used along with a Platform Backend (e.g. GLFW, SDL, Win32, custom..)

 // Implemented features:
-//  [!] Renderer: User texture binding. Use 'VkDescriptorSet' as ImTextureID. Read the FAQ about ImTextureID! See https://github.com/ocornut/imgui/pull/914 for discussions.
+//  [x] Renderer: User texture binding. Use 'VkDescriptorSet' as ImTextureID. Read the FAQ about ImTextureID! See https://github.com/ocornut/imgui/pull/914 for discussions.
 //  [X] Renderer: Large meshes support (64k+ vertices) with 16-bit indices.
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+//  [x] Renderer: Multi-viewport / platform windows. With issues (flickering when creating a new viewport).

 // The aim of imgui_impl_vulkan.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
@@ -145,8 +146,8 @@ struct ImGui_ImplVulkanH_Frame;
 struct ImGui_ImplVulkanH_Window;

 // Helpers
-IMGUI_IMPL_API void                 ImGui_ImplVulkanH_CreateOrResizeWindow(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wnd, uint32_t queue_family, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count);
-IMGUI_IMPL_API void                 ImGui_ImplVulkanH_DestroyWindow(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Window* wnd, const VkAllocationCallbacks* allocator);
+IMGUI_IMPL_API void                 ImGui_ImplVulkanH_CreateOrResizeWindow(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count);
+IMGUI_IMPL_API void                 ImGui_ImplVulkanH_DestroyWindow(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator);
 IMGUI_IMPL_API VkSurfaceFormatKHR   ImGui_ImplVulkanH_SelectSurfaceFormat(VkPhysicalDevice physical_device, VkSurfaceKHR surface, const VkFormat* request_formats, int request_formats_count, VkColorSpaceKHR request_color_space);
 IMGUI_IMPL_API VkPresentModeKHR     ImGui_ImplVulkanH_SelectPresentMode(VkPhysicalDevice physical_device, VkSurfaceKHR surface, const VkPresentModeKHR* request_modes, int request_modes_count);
 IMGUI_IMPL_API int                  ImGui_ImplVulkanH_GetMinImageCountFromPresentMode(VkPresentModeKHR present_mode);
@@ -181,7 +182,6 @@ struct ImGui_ImplVulkanH_Window
    VkSurfaceFormatKHR  SurfaceFormat;
    VkPresentModeKHR    PresentMode;
    VkRenderPass        RenderPass;
-    VkPipeline          Pipeline;               // The window pipeline may uses a different VkRenderPass than the one passed in ImGui_ImplVulkan_InitInfo
    bool                UseDynamicRendering;
    bool                ClearEnable;
    VkClearValue        ClearValue;
@@ -7,6 +7,7 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy VK_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
 //  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.

 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -21,6 +22,9 @@

 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2024-10-28: [Docking] Rely on property stored inside HWND to retrieve context/viewport, should facilitate attempt to use this for parallel contexts. (#8069)
+//  2024-09-16: [Docking] Inputs: fixed an issue where a viewport destroyed while clicking would hog mouse tracking and temporary lead to incorrect update of HoveredWindow. (#7971)
 //  2024-07-08: Inputs: Fixed ImGuiMod_Super being mapped to VK_APPS instead of VK_LWIN||VK_RWIN. (#7768)
 //  2023-10-05: Inputs: Added support for extra ImGuiKey values: F13 to F24 function keys, app back/forward keys.
 //  2023-09-25: Inputs: Synthesize key-down event on key-up for VK_SNAPSHOT / ImGuiKey_PrintScreen as Windows doesn't emit it (same behavior as GLFW/SDL).
@@ -103,6 +107,11 @@ typedef DWORD(WINAPI* PFN_XInputGetState)(DWORD, XINPUT_STATE*);
 #pragma GCC diagnostic ignored "-Wcast-function-type"       // warning: cast between incompatible function types (for loader)
 #endif

+// Forward Declarations
+static void ImGui_ImplWin32_InitMultiViewportSupport(bool platform_has_own_dc);
+static void ImGui_ImplWin32_ShutdownMultiViewportSupport();
+static void ImGui_ImplWin32_UpdateMonitors();
+
 struct ImGui_ImplWin32_Data
 {
    HWND                        hWnd;
@@ -113,6 +122,7 @@ struct ImGui_ImplWin32_Data
    INT64                       TicksPerSecond;
    ImGuiMouseCursor            LastMouseCursor;
    UINT32                      KeyboardCodePage;
+    bool                        WantUpdateMonitors;

 #ifndef IMGUI_IMPL_WIN32_DISABLE_GAMEPAD
    bool                        HasGamepad;
@@ -167,6 +177,8 @@ static bool ImGui_ImplWin32_InitEx(void* hwnd, bool platform_has_own_dc)
    io.BackendPlatformName = "imgui_impl_win32";
    io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;         // We can honor GetMouseCursor() values (optional)
    io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
+    io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;    // We can create multi-viewports on the Platform side (optional)
+    io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport; // We can call io.AddMouseViewportEvent() with correct data (optional)

    bd->hWnd = (HWND)hwnd;
    bd->TicksPerSecond = perf_frequency;
@@ -174,10 +186,15 @@ static bool ImGui_ImplWin32_InitEx(void* hwnd, bool platform_has_own_dc)
    bd->LastMouseCursor = ImGuiMouseCursor_COUNT;
    ImGui_ImplWin32_UpdateKeyboardCodePage(io);

-    // Set platform dependent data in viewport
+    // Update monitor a first time during init
+    ImGui_ImplWin32_UpdateMonitors();
+
+    // Our mouse update function expect PlatformHandle to be filled for the main viewport
    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
    main_viewport->PlatformHandle = main_viewport->PlatformHandleRaw = (void*)bd->hWnd;
-    IM_UNUSED(platform_has_own_dc); // Used in 'docking' branch
+    ::SetPropA(bd->hWnd, "IMGUI_CONTEXT", ImGui::GetCurrentContext());
+    ::SetPropA(bd->hWnd, "IMGUI_VIEWPORT", main_viewport);
+    ImGui_ImplWin32_InitMultiViewportSupport(platform_has_own_dc);

    // Dynamically load XInput library
 #ifndef IMGUI_IMPL_WIN32_DISABLE_GAMEPAD
@@ -220,6 +237,10 @@ void    ImGui_ImplWin32_Shutdown()
    IM_ASSERT(bd != nullptr && "No platform backend to shutdown, or already shutdown?");
    ImGuiIO& io = ImGui::GetIO();

+    ::SetPropA(bd->hWnd, "IMGUI_CONTEXT", nullptr);
+    ::SetPropA(bd->hWnd, "IMGUI_VIEWPORT", nullptr);
+    ImGui_ImplWin32_ShutdownMultiViewportSupport();
+
    // Unload XInput library
 #ifndef IMGUI_IMPL_WIN32_DISABLE_GAMEPAD
    if (bd->XInputDLL)
@@ -228,7 +249,7 @@ void    ImGui_ImplWin32_Shutdown()

    io.BackendPlatformName = nullptr;
    io.BackendPlatformUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad);
+    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
    IM_DELETE(bd);
 }

@@ -298,32 +319,66 @@ static void ImGui_ImplWin32_UpdateKeyModifiers(ImGuiIO& io)
    io.AddKeyEvent(ImGuiMod_Super, IsVkDown(VK_LWIN) || IsVkDown(VK_RWIN));
 }

+static ImGuiViewport* ImGui_ImplWin32_FindViewportByPlatformHandle(HWND hwnd)
+{
+    // We could use ImGui::FindViewportByPlatformHandle() but GetPropA() gets us closer to parallel multi-contexts,
+    // until we can pass an explicit context to FindViewportByPlatformHandle().
+    //return ImGui::FindViewportByPlatformHandle((void*)hwnd);
+    return (ImGuiViewport*)::GetPropA(hwnd, "IMGUI_VIEWPORT");
+}
+
+// This code supports multi-viewports (multiple OS Windows mapped into different Dear ImGui viewports)
+// Because of that, it is a little more complicated than your typical single-viewport binding code!
 static void ImGui_ImplWin32_UpdateMouseData(ImGuiIO& io)
 {
    ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData(io);
    IM_ASSERT(bd->hWnd != 0);

+    POINT mouse_screen_pos;
+    bool has_mouse_screen_pos = ::GetCursorPos(&mouse_screen_pos) != 0;
+
    HWND focused_window = ::GetForegroundWindow();
-    const bool is_app_focused = (focused_window == bd->hWnd);
+    const bool is_app_focused = (focused_window && (focused_window == bd->hWnd || ::IsChild(focused_window, bd->hWnd) || ImGui_ImplWin32_FindViewportByPlatformHandle(focused_window)));
    if (is_app_focused)
    {
        // (Optional) Set OS mouse position from Dear ImGui if requested (rarely used, only when io.ConfigNavMoveSetMousePos is enabled by user)
+        // When multi-viewports are enabled, all Dear ImGui positions are same as OS positions.
        if (io.WantSetMousePos)
        {
            POINT pos = { (int)io.MousePos.x, (int)io.MousePos.y };
-            if (::ClientToScreen(bd->hWnd, &pos))
-                ::SetCursorPos(pos.x, pos.y);
+            if ((io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) == 0)
+                ::ClientToScreen(focused_window, &pos);
+            ::SetCursorPos(pos.x, pos.y);
        }

        // (Optional) Fallback to provide mouse position when focused (WM_MOUSEMOVE already provides this when hovered or captured)
        // This also fills a short gap when clicking non-client area: WM_NCMOUSELEAVE -> modal OS move -> gap -> WM_NCMOUSEMOVE
-        if (!io.WantSetMousePos && bd->MouseTrackedArea == 0)
+        if (!io.WantSetMousePos && bd->MouseTrackedArea == 0 && has_mouse_screen_pos)
        {
-            POINT pos;
-            if (::GetCursorPos(&pos) && ::ScreenToClient(bd->hWnd, &pos))
-                io.AddMousePosEvent((float)pos.x, (float)pos.y);
+            // Single viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
+            // (This is the position you can get with ::GetCursorPos() + ::ScreenToClient() or WM_MOUSEMOVE.)
+            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
+            // (This is the position you can get with ::GetCursorPos() or WM_MOUSEMOVE + ::ClientToScreen(). In theory adding viewport->Pos to a client position would also be the same.)
+            POINT mouse_pos = mouse_screen_pos;
+            if (!(io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable))
+                ::ScreenToClient(bd->hWnd, &mouse_pos);
+            io.AddMousePosEvent((float)mouse_pos.x, (float)mouse_pos.y);
        }
    }
+
+    // (Optional) When using multiple viewports: call io.AddMouseViewportEvent() with the viewport the OS mouse cursor is hovering.
+    // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, Dear imGui will ignore this field and infer the information using its flawed heuristic.
+    // - [X] Win32 backend correctly ignore viewports with the _NoInputs flag (here using ::WindowFromPoint with WM_NCHITTEST + HTTRANSPARENT in WndProc does that)
+    //       Some backend are not able to handle that correctly. If a backend report an hovered viewport that has the _NoInputs flag (e.g. when dragging a window
+    //       for docking, the viewport has the _NoInputs flag in order to allow us to find the viewport under), then Dear ImGui is forced to ignore the value reported
+    //       by the backend, and use its flawed heuristic to guess the viewport behind.
+    // - [X] Win32 backend correctly reports this regardless of another viewport behind focused and dragged from (we need this to find a useful drag and drop target).
+    ImGuiID mouse_viewport_id = 0;
+    if (has_mouse_screen_pos)
+        if (HWND hovered_hwnd = ::WindowFromPoint(mouse_screen_pos))
+            if (ImGuiViewport* viewport = ImGui_ImplWin32_FindViewportByPlatformHandle(hovered_hwnd))
+                mouse_viewport_id = viewport->ID;
+    io.AddMouseViewportEvent(mouse_viewport_id);
 }

 // Gamepad navigation mapping
@@ -384,6 +439,37 @@ static void ImGui_ImplWin32_UpdateGamepads(ImGuiIO& io)
 #endif
 }

+static BOOL CALLBACK ImGui_ImplWin32_UpdateMonitors_EnumFunc(HMONITOR monitor, HDC, LPRECT, LPARAM)
+{
+    MONITORINFO info = {};
+    info.cbSize = sizeof(MONITORINFO);
+    if (!::GetMonitorInfo(monitor, &info))
+        return TRUE;
+    ImGuiPlatformMonitor imgui_monitor;
+    imgui_monitor.MainPos = ImVec2((float)info.rcMonitor.left, (float)info.rcMonitor.top);
+    imgui_monitor.MainSize = ImVec2((float)(info.rcMonitor.right - info.rcMonitor.left), (float)(info.rcMonitor.bottom - info.rcMonitor.top));
+    imgui_monitor.WorkPos = ImVec2((float)info.rcWork.left, (float)info.rcWork.top);
+    imgui_monitor.WorkSize = ImVec2((float)(info.rcWork.right - info.rcWork.left), (float)(info.rcWork.bottom - info.rcWork.top));
+    imgui_monitor.DpiScale = ImGui_ImplWin32_GetDpiScaleForMonitor(monitor);
+    imgui_monitor.PlatformHandle = (void*)monitor;
+    if (imgui_monitor.DpiScale <= 0.0f)
+        return TRUE; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
+    ImGuiPlatformIO& io = ImGui::GetPlatformIO();
+    if (info.dwFlags & MONITORINFOF_PRIMARY)
+        io.Monitors.push_front(imgui_monitor);
+    else
+        io.Monitors.push_back(imgui_monitor);
+    return TRUE;
+}
+
+static void ImGui_ImplWin32_UpdateMonitors()
+{
+    ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
+    ImGui::GetPlatformIO().Monitors.resize(0);
+    ::EnumDisplayMonitors(nullptr, nullptr, ImGui_ImplWin32_UpdateMonitors_EnumFunc, 0);
+    bd->WantUpdateMonitors = false;
+}
+
 void    ImGui_ImplWin32_NewFrame()
 {
    ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
@@ -394,6 +480,8 @@ void    ImGui_ImplWin32_NewFrame()
    RECT rect = { 0, 0, 0, 0 };
    ::GetClientRect(bd->hWnd, &rect);
    io.DisplaySize = ImVec2((float)(rect.right - rect.left), (float)(rect.bottom - rect.top));
+    if (bd->WantUpdateMonitors)
+        ImGui_ImplWin32_UpdateMonitors();

    // Setup time step
    INT64 current_time = 0;
@@ -618,8 +706,11 @@ IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandlerEx(HWND hwnd, UINT msg, WPA
            bd->MouseTrackedArea = area;
        }
        POINT mouse_pos = { (LONG)GET_X_LPARAM(lParam), (LONG)GET_Y_LPARAM(lParam) };
-        if (msg == WM_NCMOUSEMOVE && ::ScreenToClient(hwnd, &mouse_pos) == FALSE) // WM_NCMOUSEMOVE are provided in absolute coordinates.
-            return 0;
+        bool want_absolute_pos = (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) != 0;
+        if (msg == WM_MOUSEMOVE && want_absolute_pos)    // WM_MOUSEMOVE are client-relative coordinates.
+            ::ClientToScreen(hwnd, &mouse_pos);
+        if (msg == WM_NCMOUSEMOVE && !want_absolute_pos) // WM_NCMOUSEMOVE are absolute coordinates.
+            ::ScreenToClient(hwnd, &mouse_pos);
        io.AddMouseSourceEvent(mouse_source);
        io.AddMousePosEvent((float)mouse_pos.x, (float)mouse_pos.y);
        return 0;
@@ -765,6 +856,9 @@ IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandlerEx(HWND hwnd, UINT msg, WPA
            bd->WantUpdateHasGamepad = true;
 #endif
        return 0;
+    case WM_DISPLAYCHANGE:
+        bd->WantUpdateMonitors = true;
+        return 0;
    }
    return 0;
 }
@@ -829,6 +923,10 @@ typedef DPI_AWARENESS_CONTEXT(WINAPI* PFN_SetThreadDpiAwarenessContext)(DPI_AWAR
 // Helper function to enable DPI awareness without setting up a manifest
 void ImGui_ImplWin32_EnableDpiAwareness()
 {
+    // Make sure monitors will be updated with latest correct scaling
+    if (ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData())
+        bd->WantUpdateMonitors = true;
+
    if (_IsWindows10OrGreater())
    {
        static HINSTANCE user32_dll = ::LoadLibraryA("user32.dll"); // Reference counted per-process
@@ -928,6 +1026,381 @@ void ImGui_ImplWin32_EnableAlphaCompositing(void* hwnd)
    }
 }

+//---------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplWin32_ViewportData
+{
+    HWND    Hwnd;
+    HWND    HwndParent;
+    bool    HwndOwned;
+    DWORD   DwStyle;
+    DWORD   DwExStyle;
+
+    ImGui_ImplWin32_ViewportData() { Hwnd = HwndParent = nullptr; HwndOwned = false;  DwStyle = DwExStyle = 0; }
+    ~ImGui_ImplWin32_ViewportData() { IM_ASSERT(Hwnd == nullptr); }
+};
+
+static void ImGui_ImplWin32_GetWin32StyleFromViewportFlags(ImGuiViewportFlags flags, DWORD* out_style, DWORD* out_ex_style)
+{
+    if (flags & ImGuiViewportFlags_NoDecoration)
+        *out_style = WS_POPUP;
+    else
+        *out_style = WS_OVERLAPPEDWINDOW;
+
+    if (flags & ImGuiViewportFlags_NoTaskBarIcon)
+        *out_ex_style = WS_EX_TOOLWINDOW;
+    else
+        *out_ex_style = WS_EX_APPWINDOW;
+
+    if (flags & ImGuiViewportFlags_TopMost)
+        *out_ex_style |= WS_EX_TOPMOST;
+}
+
+static HWND ImGui_ImplWin32_GetHwndFromViewportID(ImGuiID viewport_id)
+{
+    if (viewport_id != 0)
+        if (ImGuiViewport* viewport = ImGui::FindViewportByID(viewport_id))
+            return (HWND)viewport->PlatformHandle;
+    return nullptr;
+}
+
+static void ImGui_ImplWin32_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = IM_NEW(ImGui_ImplWin32_ViewportData)();
+    viewport->PlatformUserData = vd;
+
+    // Select style and parent window
+    ImGui_ImplWin32_GetWin32StyleFromViewportFlags(viewport->Flags, &vd->DwStyle, &vd->DwExStyle);
+    vd->HwndParent = ImGui_ImplWin32_GetHwndFromViewportID(viewport->ParentViewportId);
+
+    // Create window
+    RECT rect = { (LONG)viewport->Pos.x, (LONG)viewport->Pos.y, (LONG)(viewport->Pos.x + viewport->Size.x), (LONG)(viewport->Pos.y + viewport->Size.y) };
+    ::AdjustWindowRectEx(&rect, vd->DwStyle, FALSE, vd->DwExStyle);
+    vd->Hwnd = ::CreateWindowExW(
+        vd->DwExStyle, L"ImGui Platform", L"Untitled", vd->DwStyle,       // Style, class name, window name
+        rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top,    // Window area
+        vd->HwndParent, nullptr, ::GetModuleHandle(nullptr), nullptr);          // Owner window, Menu, Instance, Param
+    vd->HwndOwned = true;
+    viewport->PlatformRequestResize = false;
+    viewport->PlatformHandle = viewport->PlatformHandleRaw = vd->Hwnd;
+
+    // Secondary viewports store their imgui context
+    ::SetPropA(vd->Hwnd, "IMGUI_CONTEXT", ImGui::GetCurrentContext());
+    ::SetPropA(vd->Hwnd, "IMGUI_VIEWPORT", viewport);
+}
+
+static void ImGui_ImplWin32_DestroyWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
+    if (ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData)
+    {
+        if (::GetCapture() == vd->Hwnd)
+        {
+            // Transfer capture so if we started dragging from a window that later disappears, we'll still receive the MOUSEUP event.
+            ::ReleaseCapture();
+            ::SetCapture(bd->hWnd);
+        }
+        if (vd->Hwnd && vd->HwndOwned)
+            ::DestroyWindow(vd->Hwnd);
+        vd->Hwnd = nullptr;
+        IM_DELETE(vd);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = nullptr;
+}
+
+static void ImGui_ImplWin32_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+
+    // ShowParent() also brings parent to front, which is not always desirable,
+    // so we temporarily disable parenting. (#7354)
+    if (vd->HwndParent != NULL)
+        ::SetWindowLongPtr(vd->Hwnd, GWLP_HWNDPARENT, (LONG_PTR)nullptr);
+
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+        ::ShowWindow(vd->Hwnd, SW_SHOWNA);
+    else
+        ::ShowWindow(vd->Hwnd, SW_SHOW);
+
+    // Restore
+    if (vd->HwndParent != NULL)
+        ::SetWindowLongPtr(vd->Hwnd, GWLP_HWNDPARENT, (LONG_PTR)vd->HwndParent);
+}
+
+static void ImGui_ImplWin32_UpdateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+
+    // Update Win32 parent if it changed _after_ creation
+    // Unlike style settings derived from configuration flags, this is more likely to change for advanced apps that are manipulating ParentViewportID manually.
+    HWND new_parent = ImGui_ImplWin32_GetHwndFromViewportID(viewport->ParentViewportId);
+    if (new_parent != vd->HwndParent)
+    {
+        // Win32 windows can either have a "Parent" (for WS_CHILD window) or an "Owner" (which among other thing keeps window above its owner).
+        // Our Dear Imgui-side concept of parenting only mostly care about what Win32 call "Owner".
+        // The parent parameter of CreateWindowEx() sets up Parent OR Owner depending on WS_CHILD flag. In our case an Owner as we never use WS_CHILD.
+        // Calling ::SetParent() here would be incorrect: it will create a full child relation, alter coordinate system and clipping.
+        // Calling ::SetWindowLongPtr() with GWLP_HWNDPARENT seems correct although poorly documented.
+        // https://devblogs.microsoft.com/oldnewthing/20100315-00/?p=14613
+        vd->HwndParent = new_parent;
+        ::SetWindowLongPtr(vd->Hwnd, GWLP_HWNDPARENT, (LONG_PTR)vd->HwndParent);
+    }
+
+    // (Optional) Update Win32 style if it changed _after_ creation.
+    // Generally they won't change unless configuration flags are changed, but advanced uses (such as manually rewriting viewport flags) make this useful.
+    DWORD new_style;
+    DWORD new_ex_style;
+    ImGui_ImplWin32_GetWin32StyleFromViewportFlags(viewport->Flags, &new_style, &new_ex_style);
+
+    // Only reapply the flags that have been changed from our point of view (as other flags are being modified by Windows)
+    if (vd->DwStyle != new_style || vd->DwExStyle != new_ex_style)
+    {
+        // (Optional) Update TopMost state if it changed _after_ creation
+        bool top_most_changed = (vd->DwExStyle & WS_EX_TOPMOST) != (new_ex_style & WS_EX_TOPMOST);
+        HWND insert_after = top_most_changed ? ((viewport->Flags & ImGuiViewportFlags_TopMost) ? HWND_TOPMOST : HWND_NOTOPMOST) : 0;
+        UINT swp_flag = top_most_changed ? 0 : SWP_NOZORDER;
+
+        // Apply flags and position (since it is affected by flags)
+        vd->DwStyle = new_style;
+        vd->DwExStyle = new_ex_style;
+        ::SetWindowLong(vd->Hwnd, GWL_STYLE, vd->DwStyle);
+        ::SetWindowLong(vd->Hwnd, GWL_EXSTYLE, vd->DwExStyle);
+        RECT rect = { (LONG)viewport->Pos.x, (LONG)viewport->Pos.y, (LONG)(viewport->Pos.x + viewport->Size.x), (LONG)(viewport->Pos.y + viewport->Size.y) };
+        ::AdjustWindowRectEx(&rect, vd->DwStyle, FALSE, vd->DwExStyle); // Client to Screen
+        ::SetWindowPos(vd->Hwnd, insert_after, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, swp_flag | SWP_NOACTIVATE | SWP_FRAMECHANGED);
+        ::ShowWindow(vd->Hwnd, SW_SHOWNA); // This is necessary when we alter the style
+        viewport->PlatformRequestMove = viewport->PlatformRequestResize = true;
+    }
+}
+
+static ImVec2 ImGui_ImplWin32_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    POINT pos = { 0, 0 };
+    ::ClientToScreen(vd->Hwnd, &pos);
+    return ImVec2((float)pos.x, (float)pos.y);
+}
+
+static void ImGui_ImplWin32_UpdateWin32StyleFromWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    vd->DwStyle = ::GetWindowLongW(vd->Hwnd, GWL_STYLE);
+    vd->DwExStyle = ::GetWindowLongW(vd->Hwnd, GWL_EXSTYLE);
+}
+
+static void ImGui_ImplWin32_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    RECT rect = { (LONG)pos.x, (LONG)pos.y, (LONG)pos.x, (LONG)pos.y };
+    if (viewport->Flags & ImGuiViewportFlags_OwnedByApp)
+        ImGui_ImplWin32_UpdateWin32StyleFromWindow(viewport); // Not our window, poll style before using
+    ::AdjustWindowRectEx(&rect, vd->DwStyle, FALSE, vd->DwExStyle);
+    ::SetWindowPos(vd->Hwnd, nullptr, rect.left, rect.top, 0, 0, SWP_NOZORDER | SWP_NOSIZE | SWP_NOACTIVATE);
+}
+
+static ImVec2 ImGui_ImplWin32_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    RECT rect;
+    ::GetClientRect(vd->Hwnd, &rect);
+    return ImVec2(float(rect.right - rect.left), float(rect.bottom - rect.top));
+}
+
+static void ImGui_ImplWin32_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    RECT rect = { 0, 0, (LONG)size.x, (LONG)size.y };
+    if (viewport->Flags & ImGuiViewportFlags_OwnedByApp)
+        ImGui_ImplWin32_UpdateWin32StyleFromWindow(viewport); // Not our window, poll style before using
+    ::AdjustWindowRectEx(&rect, vd->DwStyle, FALSE, vd->DwExStyle); // Client to Screen
+    ::SetWindowPos(vd->Hwnd, nullptr, 0, 0, rect.right - rect.left, rect.bottom - rect.top, SWP_NOZORDER | SWP_NOMOVE | SWP_NOACTIVATE);
+}
+
+static void ImGui_ImplWin32_SetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    ::BringWindowToTop(vd->Hwnd);
+    ::SetForegroundWindow(vd->Hwnd);
+    ::SetFocus(vd->Hwnd);
+}
+
+static bool ImGui_ImplWin32_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    return ::GetForegroundWindow() == vd->Hwnd;
+}
+
+static bool ImGui_ImplWin32_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    return ::IsIconic(vd->Hwnd) != 0;
+}
+
+static void ImGui_ImplWin32_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    // ::SetWindowTextA() doesn't properly handle UTF-8 so we explicitely convert our string.
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    int n = ::MultiByteToWideChar(CP_UTF8, 0, title, -1, nullptr, 0);
+    ImVector<wchar_t> title_w;
+    title_w.resize(n);
+    ::MultiByteToWideChar(CP_UTF8, 0, title, -1, title_w.Data, n);
+    ::SetWindowTextW(vd->Hwnd, title_w.Data);
+}
+
+static void ImGui_ImplWin32_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    IM_ASSERT(alpha >= 0.0f && alpha <= 1.0f);
+    if (alpha < 1.0f)
+    {
+        DWORD ex_style = ::GetWindowLongW(vd->Hwnd, GWL_EXSTYLE) | WS_EX_LAYERED;
+        ::SetWindowLongW(vd->Hwnd, GWL_EXSTYLE, ex_style);
+        ::SetLayeredWindowAttributes(vd->Hwnd, 0, (BYTE)(255 * alpha), LWA_ALPHA);
+    }
+    else
+    {
+        DWORD ex_style = ::GetWindowLongW(vd->Hwnd, GWL_EXSTYLE) & ~WS_EX_LAYERED;
+        ::SetWindowLongW(vd->Hwnd, GWL_EXSTYLE, ex_style);
+    }
+}
+
+static float ImGui_ImplWin32_GetWindowDpiScale(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    return ImGui_ImplWin32_GetDpiScaleForHwnd(vd->Hwnd);
+}
+
+// FIXME-DPI: Testing DPI related ideas
+static void ImGui_ImplWin32_OnChangedViewport(ImGuiViewport* viewport)
+{
+    (void)viewport;
+#if 0
+    ImGuiStyle default_style;
+    //default_style.WindowPadding = ImVec2(0, 0);
+    //default_style.WindowBorderSize = 0.0f;
+    //default_style.ItemSpacing.y = 3.0f;
+    //default_style.FramePadding = ImVec2(0, 0);
+    default_style.ScaleAllSizes(viewport->DpiScale);
+    ImGuiStyle& style = ImGui::GetStyle();
+    style = default_style;
+#endif
+}
+
+namespace ImGui { extern ImGuiIO& GetIOEx(ImGuiContext*); }
+
+static LRESULT CALLBACK ImGui_ImplWin32_WndProcHandler_PlatformWindow(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+    // Allow secondary viewport WndProc to be called regardless of current context
+    ImGuiContext* ctx = (ImGuiContext*)::GetPropA(hWnd, "IMGUI_CONTEXT");
+    if (ctx == NULL)
+        return DefWindowProc(hWnd, msg, wParam, lParam); // unlike ImGui_ImplWin32_WndProcHandler() we are called directly by Windows, we can't just return 0.
+
+    ImGuiIO& io = ImGui::GetIOEx(ctx);
+    LRESULT result = 0;
+    if (ImGui_ImplWin32_WndProcHandlerEx(hWnd, msg, wParam, lParam, io))
+        result = true;
+    else if (ImGuiViewport* viewport = ImGui_ImplWin32_FindViewportByPlatformHandle(hWnd))
+    {
+        switch (msg)
+        {
+        case WM_CLOSE:
+            viewport->PlatformRequestClose = true;
+            break;
+        case WM_MOVE:
+            viewport->PlatformRequestMove = true;
+            break;
+        case WM_SIZE:
+            viewport->PlatformRequestResize = true;
+            break;
+        case WM_MOUSEACTIVATE:
+            if (viewport->Flags & ImGuiViewportFlags_NoFocusOnClick)
+                result = MA_NOACTIVATE;
+            break;
+        case WM_NCHITTEST:
+            // Let mouse pass-through the window. This will allow the backend to call io.AddMouseViewportEvent() correctly. (which is optional).
+            // The ImGuiViewportFlags_NoInputs flag is set while dragging a viewport, as want to detect the window behind the one we are dragging.
+            // If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
+            // your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
+            if (viewport->Flags & ImGuiViewportFlags_NoInputs)
+                result = HTTRANSPARENT;
+            break;
+        }
+    }
+    if (result == 0)
+        result = DefWindowProc(hWnd, msg, wParam, lParam);
+    return result;
+}
+
+static void ImGui_ImplWin32_InitMultiViewportSupport(bool platform_has_own_dc)
+{
+    WNDCLASSEXW wcex;
+    wcex.cbSize = sizeof(WNDCLASSEXW);
+    wcex.style = CS_HREDRAW | CS_VREDRAW | (platform_has_own_dc ? CS_OWNDC : 0);
+    wcex.lpfnWndProc = ImGui_ImplWin32_WndProcHandler_PlatformWindow;
+    wcex.cbClsExtra = 0;
+    wcex.cbWndExtra = 0;
+    wcex.hInstance = ::GetModuleHandle(nullptr);
+    wcex.hIcon = nullptr;
+    wcex.hCursor = nullptr;
+    wcex.hbrBackground = (HBRUSH)(COLOR_BACKGROUND + 1);
+    wcex.lpszMenuName = nullptr;
+    wcex.lpszClassName = L"ImGui Platform";
+    wcex.hIconSm = nullptr;
+    ::RegisterClassExW(&wcex);
+
+    ImGui_ImplWin32_UpdateMonitors();
+
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplWin32_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplWin32_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplWin32_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplWin32_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplWin32_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplWin32_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplWin32_GetWindowSize;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplWin32_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplWin32_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplWin32_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplWin32_SetWindowTitle;
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplWin32_SetWindowAlpha;
+    platform_io.Platform_UpdateWindow = ImGui_ImplWin32_UpdateWindow;
+    platform_io.Platform_GetWindowDpiScale = ImGui_ImplWin32_GetWindowDpiScale; // FIXME-DPI
+    platform_io.Platform_OnChangedViewport = ImGui_ImplWin32_OnChangedViewport; // FIXME-DPI
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
+    ImGui_ImplWin32_ViewportData* vd = IM_NEW(ImGui_ImplWin32_ViewportData)();
+    vd->Hwnd = bd->hWnd;
+    vd->HwndOwned = false;
+    main_viewport->PlatformUserData = vd;
+}
+
+static void ImGui_ImplWin32_ShutdownMultiViewportSupport()
+{
+    ::UnregisterClass(_T("ImGui Platform"), ::GetModuleHandle(nullptr));
+    ImGui::DestroyPlatformWindows();
+}
+
 //---------------------------------------------------------------------------------------------------------

 #if defined(__GNUC__)
@@ -7,6 +7,7 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy VK_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
 //  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.

 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -31,6 +31,8 @@
 #define IMGUI_VERSION       "1.91.5"
 #define IMGUI_VERSION_NUM   19150
 #define IMGUI_HAS_TABLE
+#define IMGUI_HAS_VIEWPORT          // Viewport WIP branch
+#define IMGUI_HAS_DOCK              // Docking WIP branch

 /*

@@ -43,13 +45,13 @@ Index of this file:
 // [SECTION] Helpers: Debug log, Memory allocations macros, ImVector<>
 // [SECTION] ImGuiStyle
 // [SECTION] ImGuiIO
-// [SECTION] Misc data structures (ImGuiInputTextCallbackData, ImGuiSizeCallbackData, ImGuiPayload)
+// [SECTION] Misc data structures (ImGuiInputTextCallbackData, ImGuiSizeCallbackData, ImGuiWindowClass, ImGuiPayload)
 // [SECTION] Helpers (ImGuiOnceUponAFrame, ImGuiTextFilter, ImGuiTextBuffer, ImGuiStorage, ImGuiListClipper, Math Operators, ImColor)
 // [SECTION] Multi-Select API flags and structures (ImGuiMultiSelectFlags, ImGuiMultiSelectIO, ImGuiSelectionRequest, ImGuiSelectionBasicStorage, ImGuiSelectionExternalStorage)
 // [SECTION] Drawing API (ImDrawCallback, ImDrawCmd, ImDrawIdx, ImDrawVert, ImDrawChannel, ImDrawListSplitter, ImDrawFlags, ImDrawListFlags, ImDrawList, ImDrawData)
 // [SECTION] Font API (ImFontConfig, ImFontGlyph, ImFontGlyphRangesBuilder, ImFontAtlasFlags, ImFontAtlas, ImFont)
 // [SECTION] Viewports (ImGuiViewportFlags, ImGuiViewport)
-// [SECTION] ImGuiPlatformIO + other Platform Dependent Interfaces (ImGuiPlatformImeData)
+// [SECTION] ImGuiPlatformIO + other Platform Dependent Interfaces (ImGuiPlatformMonitor, ImGuiPlatformImeData)
 // [SECTION] Obsolete functions and types

 */
@@ -180,8 +182,9 @@ struct ImGuiListClipper;            // Helper to manually clip large list of ite
 struct ImGuiMultiSelectIO;          // Structure to interact with a BeginMultiSelect()/EndMultiSelect() block
 struct ImGuiOnceUponAFrame;         // Helper for running a block of code not more than once a frame
 struct ImGuiPayload;                // User data payload for drag and drop operations
-struct ImGuiPlatformIO;             // Interface between platform/renderer backends and ImGui (e.g. Clipboard, IME hooks). Extends ImGuiIO. In docking branch, this gets extended to support multi-viewports.
+struct ImGuiPlatformIO;             // Interface between platform/renderer backends and ImGui (e.g. Clipboard, IME, Multi-Viewport support). Extends ImGuiIO.
 struct ImGuiPlatformImeData;        // Platform IME data for io.PlatformSetImeDataFn() function.
+struct ImGuiPlatformMonitor;        // Multi-viewport support: user-provided bounds for each connected monitor/display. Used when positioning popups and tooltips to avoid them straddling monitors
 struct ImGuiSelectionBasicStorage;  // Optional helper to store multi-selection state + apply multi-selection requests.
 struct ImGuiSelectionExternalStorage;//Optional helper to apply multi-selection requests to existing randomly accessible storage.
 struct ImGuiSelectionRequest;       // A selection request (stored in ImGuiMultiSelectIO)
@@ -193,7 +196,8 @@ struct ImGuiTableSortSpecs;         // Sorting specifications for a table (often
 struct ImGuiTableColumnSortSpecs;   // Sorting specification for one column of a table
 struct ImGuiTextBuffer;             // Helper to hold and append into a text buffer (~string builder)
 struct ImGuiTextFilter;             // Helper to parse and apply text filters (e.g. "aaaaa[,bbbbb][,ccccc]")
-struct ImGuiViewport;               // A Platform Window (always only one in 'master' branch), in the future may represent Platform Monitor
+struct ImGuiViewport;               // A Platform Window (always 1 unless multi-viewport are enabled. One per platform window to output to). In the future may represent Platform Monitor
+struct ImGuiWindowClass;            // Window class (rare/advanced uses: provide hints to the platform backend via altered viewport flags and parent/child info)

 // Enumerations
 // - We don't use strongly typed enums much because they add constraints (can't extend in private code, can't store typed in bit fields, extra casting on iteration)
@@ -227,6 +231,7 @@ typedef int ImGuiChildFlags;        // -> enum ImGuiChildFlags_      // Flags: f
 typedef int ImGuiColorEditFlags;    // -> enum ImGuiColorEditFlags_  // Flags: for ColorEdit4(), ColorPicker4() etc.
 typedef int ImGuiConfigFlags;       // -> enum ImGuiConfigFlags_     // Flags: for io.ConfigFlags
 typedef int ImGuiComboFlags;        // -> enum ImGuiComboFlags_      // Flags: for BeginCombo()
+typedef int ImGuiDockNodeFlags;     // -> enum ImGuiDockNodeFlags_   // Flags: for DockSpace()
 typedef int ImGuiDragDropFlags;     // -> enum ImGuiDragDropFlags_   // Flags: for BeginDragDropSource(), AcceptDragDropPayload()
 typedef int ImGuiFocusedFlags;      // -> enum ImGuiFocusedFlags_    // Flags: for IsWindowFocused()
 typedef int ImGuiHoveredFlags;      // -> enum ImGuiHoveredFlags_    // Flags: for IsItemHovered(), IsWindowHovered() etc.
@@ -398,10 +403,12 @@ namespace ImGui
    IMGUI_API bool          IsWindowFocused(ImGuiFocusedFlags flags=0); // is current window focused? or its root/child, depending on flags. see flags for options.
    IMGUI_API bool          IsWindowHovered(ImGuiHoveredFlags flags=0); // is current window hovered and hoverable (e.g. not blocked by a popup/modal)? See ImGuiHoveredFlags_ for options. IMPORTANT: If you are trying to check whether your mouse should be dispatched to Dear ImGui or to your underlying app, you should not use this function! Use the 'io.WantCaptureMouse' boolean for that! Refer to FAQ entry "How can I tell whether to dispatch mouse/keyboard to Dear ImGui or my application?" for details.
    IMGUI_API ImDrawList*   GetWindowDrawList();                        // get draw list associated to the current window, to append your own drawing primitives
+    IMGUI_API float         GetWindowDpiScale();                        // get DPI scale currently associated to the current window's viewport.
    IMGUI_API ImVec2        GetWindowPos();                             // get current window position in screen space (IT IS UNLIKELY YOU EVER NEED TO USE THIS. Consider always using GetCursorScreenPos() and GetContentRegionAvail() instead)
    IMGUI_API ImVec2        GetWindowSize();                            // get current window size (IT IS UNLIKELY YOU EVER NEED TO USE THIS. Consider always using GetCursorScreenPos() and GetContentRegionAvail() instead)
    IMGUI_API float         GetWindowWidth();                           // get current window width (IT IS UNLIKELY YOU EVER NEED TO USE THIS). Shortcut for GetWindowSize().x.
    IMGUI_API float         GetWindowHeight();                          // get current window height (IT IS UNLIKELY YOU EVER NEED TO USE THIS). Shortcut for GetWindowSize().y.
+    IMGUI_API ImGuiViewport*GetWindowViewport();                        // get viewport currently associated to the current window.

    // Window manipulation
    // - Prefer using SetNextXXX functions (before Begin) rather that SetXXX functions (after Begin).
@@ -413,6 +420,7 @@ namespace ImGui
    IMGUI_API void          SetNextWindowFocus();                                                       // set next window to be focused / top-most. call before Begin()
    IMGUI_API void          SetNextWindowScroll(const ImVec2& scroll);                                  // set next window scrolling value (use < 0.0f to not affect a given axis).
    IMGUI_API void          SetNextWindowBgAlpha(float alpha);                                          // set next window background color alpha. helper to easily override the Alpha component of ImGuiCol_WindowBg/ChildBg/PopupBg. you may also use ImGuiWindowFlags_NoBackground.
+    IMGUI_API void          SetNextWindowViewport(ImGuiID viewport_id);                                 // set next window viewport
    IMGUI_API void          SetWindowPos(const ImVec2& pos, ImGuiCond cond = 0);                        // (not recommended) set current window position - call within Begin()/End(). prefer using SetNextWindowPos(), as this may incur tearing and side-effects.
    IMGUI_API void          SetWindowSize(const ImVec2& size, ImGuiCond cond = 0);                      // (not recommended) set current window size - call within Begin()/End(). set to ImVec2(0, 0) to force an auto-fit. prefer using SetNextWindowSize(), as this may incur tearing and minor side-effects.
    IMGUI_API void          SetWindowCollapsed(bool collapsed, ImGuiCond cond = 0);                     // (not recommended) set current window collapsed state. prefer using SetNextWindowCollapsed().
@@ -864,6 +872,26 @@ namespace ImGui
    IMGUI_API bool          TabItemButton(const char* label, ImGuiTabItemFlags flags = 0);      // create a Tab behaving like a button. return true when clicked. cannot be selected in the tab bar.
    IMGUI_API void          SetTabItemClosed(const char* tab_or_docked_window_label);           // notify TabBar or Docking system of a closed tab/window ahead (useful to reduce visual flicker on reorderable tab bars). For tab-bar: call after BeginTabBar() and before Tab submissions. Otherwise call with a window name.

+    // Docking
+    // [BETA API] Enable with io.ConfigFlags |= ImGuiConfigFlags_DockingEnable.
+    // Note: You can use most Docking facilities without calling any API. You DO NOT need to call DockSpace() to use Docking!
+    // - Drag from window title bar or their tab to dock/undock. Hold SHIFT to disable docking.
+    // - Drag from window menu button (upper-left button) to undock an entire node (all windows).
+    // - When io.ConfigDockingWithShift == true, you instead need to hold SHIFT to enable docking.
+    // About dockspaces:
+    // - Use DockSpaceOverViewport() to create a window covering the screen or a specific viewport + a dockspace inside it.
+    //   This is often used with ImGuiDockNodeFlags_PassthruCentralNode to make it transparent.
+    // - Use DockSpace() to create an explicit dock node _within_ an existing window. See Docking demo for details.
+    // - Important: Dockspaces need to be submitted _before_ any window they can host. Submit it early in your frame!
+    // - Important: Dockspaces need to be kept alive if hidden, otherwise windows docked into it will be undocked.
+    //   e.g. if you have multiple tabs with a dockspace inside each tab: submit the non-visible dockspaces with ImGuiDockNodeFlags_KeepAliveOnly.
+    IMGUI_API ImGuiID       DockSpace(ImGuiID dockspace_id, const ImVec2& size = ImVec2(0, 0), ImGuiDockNodeFlags flags = 0, const ImGuiWindowClass* window_class = NULL);
+    IMGUI_API ImGuiID       DockSpaceOverViewport(ImGuiID dockspace_id = 0, const ImGuiViewport* viewport = NULL, ImGuiDockNodeFlags flags = 0, const ImGuiWindowClass* window_class = NULL);
+    IMGUI_API void          SetNextWindowDockID(ImGuiID dock_id, ImGuiCond cond = 0);           // set next window dock id
+    IMGUI_API void          SetNextWindowClass(const ImGuiWindowClass* window_class);           // set next window class (control docking compatibility + provide hints to platform backend via custom viewport flags and platform parent/child relationship)
+    IMGUI_API ImGuiID       GetWindowDockID();
+    IMGUI_API bool          IsWindowDocked();                                                   // is current window docked into another window?
+
    // Logging/Capture
    // - All text output from the interface can be captured into tty/file/clipboard. By default, tree nodes are automatically opened during logging.
    IMGUI_API void          LogToTTY(int auto_open_depth = -1);                                 // start logging to tty (stdout)
@@ -938,8 +966,8 @@ namespace ImGui
    IMGUI_API ImGuiViewport* GetMainViewport();                                                 // return primary/default viewport. This can never be NULL.

    // Background/Foreground Draw Lists
-    IMGUI_API ImDrawList*   GetBackgroundDrawList();                                            // this draw list will be the first rendered one. Useful to quickly draw shapes/text behind dear imgui contents.
-    IMGUI_API ImDrawList*   GetForegroundDrawList();                                            // this draw list will be the last rendered one. Useful to quickly draw shapes/text over dear imgui contents.
+    IMGUI_API ImDrawList*   GetBackgroundDrawList(ImGuiViewport* viewport = NULL);              // get background draw list for the given viewport or viewport associated to the current window. this draw list will be the first rendering one. Useful to quickly draw shapes/text behind dear imgui contents.
+    IMGUI_API ImDrawList*   GetForegroundDrawList(ImGuiViewport* viewport = NULL);              // get foreground draw list for the given viewport or viewport associated to the current window. this draw list will be the top-most rendered one. Useful to quickly draw shapes/text over dear imgui contents.

    // Miscellaneous Utilities
    IMGUI_API bool          IsRectVisible(const ImVec2& size);                                  // test if rectangle (of given size, starting from cursor position) is visible / not clipped.
@@ -1053,6 +1081,15 @@ namespace ImGui
    IMGUI_API void*         MemAlloc(size_t size);
    IMGUI_API void          MemFree(void* ptr);

+    // (Optional) Platform/OS interface for multi-viewport support
+    // Read comments around the ImGuiPlatformIO structure for more details.
+    // Note: You may use GetWindowViewport() to get the current viewport of the current window.
+    IMGUI_API void              UpdatePlatformWindows();                                        // call in main loop. will call CreateWindow/ResizeWindow/etc. platform functions for each secondary viewport, and DestroyWindow for each inactive viewport.
+    IMGUI_API void              RenderPlatformWindowsDefault(void* platform_render_arg = NULL, void* renderer_render_arg = NULL); // call in main loop. will call RenderWindow/SwapBuffers platform functions for each secondary viewport which doesn't have the ImGuiViewportFlags_Minimized flag set. May be reimplemented by user for custom rendering needs.
+    IMGUI_API void              DestroyPlatformWindows();                                       // call DestroyWindow platform functions for all viewports. call from backend Shutdown() if you need to close platform windows before imgui shutdown. otherwise will be called by DestroyContext().
+    IMGUI_API ImGuiViewport*    FindViewportByID(ImGuiID id);                                   // this is a helper for backends.
+    IMGUI_API ImGuiViewport*    FindViewportByPlatformHandle(void* platform_handle);            // this is a helper for backends. the type platform_handle is decided by the backend (e.g. HWND, MyWindow*, GLFWwindow* etc.)
+
 } // namespace ImGui

 //-----------------------------------------------------------------------------
@@ -1083,6 +1120,7 @@ enum ImGuiWindowFlags_
    ImGuiWindowFlags_NoNavInputs            = 1 << 16,  // No keyboard/gamepad navigation within the window
    ImGuiWindowFlags_NoNavFocus             = 1 << 17,  // No focusing toward this window with keyboard/gamepad navigation (e.g. skipped by CTRL+TAB)
    ImGuiWindowFlags_UnsavedDocument        = 1 << 18,  // Display a dot next to the title. When used in a tab/docking context, tab is selected when clicking the X + closure is not assumed (will wait for user to stop submitting the tab). Otherwise closure is assumed when pressing the X, so if you keep submitting the tab may reappear at end of tab bar.
+    ImGuiWindowFlags_NoDocking              = 1 << 19,  // Disable docking of this window
    ImGuiWindowFlags_NoNav                  = ImGuiWindowFlags_NoNavInputs | ImGuiWindowFlags_NoNavFocus,
    ImGuiWindowFlags_NoDecoration           = ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoCollapse,
    ImGuiWindowFlags_NoInputs               = ImGuiWindowFlags_NoMouseInputs | ImGuiWindowFlags_NoNavInputs | ImGuiWindowFlags_NoNavFocus,
@@ -1093,6 +1131,7 @@ enum ImGuiWindowFlags_
    ImGuiWindowFlags_Popup                  = 1 << 26,  // Don't use! For internal use by BeginPopup()
    ImGuiWindowFlags_Modal                  = 1 << 27,  // Don't use! For internal use by BeginPopupModal()
    ImGuiWindowFlags_ChildMenu              = 1 << 28,  // Don't use! For internal use by BeginMenu()
+    ImGuiWindowFlags_DockNodeHost           = 1 << 29,  // Don't use! For internal use by Begin()/NewFrame()

    // Obsolete names
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
@@ -1307,7 +1346,7 @@ enum ImGuiFocusedFlags_
    ImGuiFocusedFlags_RootWindow                    = 1 << 1,   // Test from root window (top most parent of the current hierarchy)
    ImGuiFocusedFlags_AnyWindow                     = 1 << 2,   // Return true if any window is focused. Important: If you are trying to tell how to dispatch your low-level inputs, do NOT use this. Use 'io.WantCaptureMouse' instead! Please read the FAQ!
    ImGuiFocusedFlags_NoPopupHierarchy              = 1 << 3,   // Do not consider popup hierarchy (do not treat popup emitter as parent of popup) (when used with _ChildWindows or _RootWindow)
-    //ImGuiFocusedFlags_DockHierarchy               = 1 << 4,   // Consider docking hierarchy (treat dockspace host as parent of docked window) (when used with _ChildWindows or _RootWindow)
+    ImGuiFocusedFlags_DockHierarchy                 = 1 << 4,   // Consider docking hierarchy (treat dockspace host as parent of docked window) (when used with _ChildWindows or _RootWindow)
    ImGuiFocusedFlags_RootAndChildWindows           = ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_ChildWindows,
 };

@@ -1321,7 +1360,7 @@ enum ImGuiHoveredFlags_
    ImGuiHoveredFlags_RootWindow                    = 1 << 1,   // IsWindowHovered() only: Test from root window (top most parent of the current hierarchy)
    ImGuiHoveredFlags_AnyWindow                     = 1 << 2,   // IsWindowHovered() only: Return true if any window is hovered
    ImGuiHoveredFlags_NoPopupHierarchy              = 1 << 3,   // IsWindowHovered() only: Do not consider popup hierarchy (do not treat popup emitter as parent of popup) (when used with _ChildWindows or _RootWindow)
-    //ImGuiHoveredFlags_DockHierarchy               = 1 << 4,   // IsWindowHovered() only: Consider docking hierarchy (treat dockspace host as parent of docked window) (when used with _ChildWindows or _RootWindow)
+    ImGuiHoveredFlags_DockHierarchy                 = 1 << 4,   // IsWindowHovered() only: Consider docking hierarchy (treat dockspace host as parent of docked window) (when used with _ChildWindows or _RootWindow)
    ImGuiHoveredFlags_AllowWhenBlockedByPopup       = 1 << 5,   // Return true even if a popup window is normally blocking access to this item/window
    //ImGuiHoveredFlags_AllowWhenBlockedByModal     = 1 << 6,   // Return true even if a modal popup window is normally blocking access to this item/window. FIXME-TODO: Unavailable yet.
    ImGuiHoveredFlags_AllowWhenBlockedByActiveItem  = 1 << 7,   // Return true even if an active item is blocking access to this item/window. Useful for Drag and Drop patterns.
@@ -1351,6 +1390,27 @@ enum ImGuiHoveredFlags_
    ImGuiHoveredFlags_NoSharedDelay                 = 1 << 17,  // IsItemHovered() only: Disable shared delay system where moving from one item to the next keeps the previous timer for a short time (standard for tooltips with long delays)
 };

+// Flags for ImGui::DockSpace(), shared/inherited by child nodes.
+// (Some flags can be applied to individual nodes directly)
+// FIXME-DOCK: Also see ImGuiDockNodeFlagsPrivate_ which may involve using the WIP and internal DockBuilder api.
+enum ImGuiDockNodeFlags_
+{
+    ImGuiDockNodeFlags_None                         = 0,
+    ImGuiDockNodeFlags_KeepAliveOnly                = 1 << 0,   //       // Don't display the dockspace node but keep it alive. Windows docked into this dockspace node won't be undocked.
+    //ImGuiDockNodeFlags_NoCentralNode              = 1 << 1,   //       // Disable Central Node (the node which can stay empty)
+    ImGuiDockNodeFlags_NoDockingOverCentralNode     = 1 << 2,   //       // Disable docking over the Central Node, which will be always kept empty.
+    ImGuiDockNodeFlags_PassthruCentralNode          = 1 << 3,   //       // Enable passthru dockspace: 1) DockSpace() will render a ImGuiCol_WindowBg background covering everything excepted the Central Node when empty. Meaning the host window should probably use SetNextWindowBgAlpha(0.0f) prior to Begin() when using this. 2) When Central Node is empty: let inputs pass-through + won't display a DockingEmptyBg background. See demo for details.
+    ImGuiDockNodeFlags_NoDockingSplit               = 1 << 4,   //       // Disable other windows/nodes from splitting this node.
+    ImGuiDockNodeFlags_NoResize                     = 1 << 5,   // Saved // Disable resizing node using the splitter/separators. Useful with programmatically setup dockspaces.
+    ImGuiDockNodeFlags_AutoHideTabBar               = 1 << 6,   //       // Tab bar will automatically hide when there is a single window in the dock node.
+    ImGuiDockNodeFlags_NoUndocking                  = 1 << 7,   //       // Disable undocking this node.
+
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+    ImGuiDockNodeFlags_NoSplit                      = ImGuiDockNodeFlags_NoDockingSplit, // Renamed in 1.90
+    ImGuiDockNodeFlags_NoDockingInCentralNode       = ImGuiDockNodeFlags_NoDockingOverCentralNode, // Renamed in 1.90
+#endif
+};
+
 // Flags for ImGui::BeginDragDropSource(), ImGui::AcceptDragDropPayload()
 enum ImGuiDragDropFlags_
 {
@@ -1580,6 +1640,15 @@ enum ImGuiConfigFlags_
    ImGuiConfigFlags_NoMouseCursorChange    = 1 << 5,   // Instruct backend to not alter mouse cursor shape and visibility. Use if the backend cursor changes are interfering with yours and you don't want to use SetMouseCursor() to change mouse cursor. You may want to honor requests from imgui by reading GetMouseCursor() yourself instead.
    ImGuiConfigFlags_NoKeyboard             = 1 << 6,   // Instruct dear imgui to disable keyboard inputs and interactions. This is done by ignoring keyboard events and clearing existing states.

+    // [BETA] Docking
+    ImGuiConfigFlags_DockingEnable          = 1 << 7,   // Docking enable flags.
+
+    // [BETA] Viewports
+    // When using viewports it is recommended that your default value for ImGuiCol_WindowBg is opaque (Alpha=1.0) so transition to a viewport won't be noticeable.
+    ImGuiConfigFlags_ViewportsEnable        = 1 << 10,  // Viewport enable flags (require both ImGuiBackendFlags_PlatformHasViewports + ImGuiBackendFlags_RendererHasViewports set by the respective backends)
+    ImGuiConfigFlags_DpiEnableScaleViewports= 1 << 14,  // [BETA: Don't use] FIXME-DPI: Reposition and resize imgui windows when the DpiScale of a viewport changed (mostly useful for the main viewport hosting other window). Note that resizing the main window itself is up to your application.
+    ImGuiConfigFlags_DpiEnableScaleFonts    = 1 << 15,  // [BETA: Don't use] FIXME-DPI: Request bitmap-scaled fonts to match DpiScale. This is a very low-quality workaround. The correct way to handle DPI is _currently_ to replace the atlas and/or fonts in the Platform_OnChangedViewport callback, but this is all early work in progress.
+
    // User storage (to allow your backend/engine to communicate to code that may be shared between multiple projects. Those flags are NOT used by core Dear ImGui)
    ImGuiConfigFlags_IsSRGB                 = 1 << 20,  // Application is SRGB-aware.
    ImGuiConfigFlags_IsTouchScreen          = 1 << 21,  // Application is using a touch screen instead of a mouse.
@@ -1598,6 +1667,11 @@ enum ImGuiBackendFlags_
    ImGuiBackendFlags_HasMouseCursors       = 1 << 1,   // Backend Platform supports honoring GetMouseCursor() value to change the OS cursor shape.
    ImGuiBackendFlags_HasSetMousePos        = 1 << 2,   // Backend Platform supports io.WantSetMousePos requests to reposition the OS mouse position (only used if io.ConfigNavMoveSetMousePos is set).
    ImGuiBackendFlags_RendererHasVtxOffset  = 1 << 3,   // Backend Renderer supports ImDrawCmd::VtxOffset. This enables output of large meshes (64K+ vertices) while still using 16-bit indices.
+
+    // [BETA] Viewports
+    ImGuiBackendFlags_PlatformHasViewports  = 1 << 10,  // Backend Platform supports multiple viewports.
+    ImGuiBackendFlags_HasMouseHoveredViewport=1 << 11,  // Backend Platform supports calling io.AddMouseViewportEvent() with the viewport under the mouse. IF POSSIBLE, ignore viewports with the ImGuiViewportFlags_NoInputs flag (Win32 backend, GLFW 3.30+ backend can do this, SDL backend cannot). If this cannot be done, Dear ImGui needs to use a flawed heuristic to find the viewport under.
+    ImGuiBackendFlags_RendererHasViewports  = 1 << 12,  // Backend Renderer supports multiple viewports.
 };

 // Enumeration for PushStyleColor() / PopStyleColor()
@@ -1643,6 +1717,8 @@ enum ImGuiCol_
    ImGuiCol_TabDimmed,             // Tab background, when tab-bar is unfocused & tab is unselected
    ImGuiCol_TabDimmedSelected,     // Tab background, when tab-bar is unfocused & tab is selected
    ImGuiCol_TabDimmedSelectedOverline,//..horizontal overline, when tab-bar is unfocused & tab is selected
+    ImGuiCol_DockingPreview,        // Preview overlay color when about to docking something
+    ImGuiCol_DockingEmptyBg,        // Background color for empty node (e.g. CentralNode with no window docked into it)
    ImGuiCol_PlotLines,
    ImGuiCol_PlotLinesHovered,
    ImGuiCol_PlotHistogram,
@@ -1713,6 +1789,7 @@ enum ImGuiStyleVar_
    ImGuiStyleVar_SeparatorTextBorderSize,  // float     SeparatorTextBorderSize
    ImGuiStyleVar_SeparatorTextAlign,       // ImVec2    SeparatorTextAlign
    ImGuiStyleVar_SeparatorTextPadding,     // ImVec2    SeparatorTextPadding
+    ImGuiStyleVar_DockingSeparatorSize,     // float     DockingSeparatorSize
    ImGuiStyleVar_COUNT
 };

@@ -2159,6 +2236,7 @@ struct ImGuiStyle
    ImVec2      SeparatorTextPadding;       // Horizontal offset of text from each edge of the separator + spacing on other axis. Generally small values. .y is recommended to be == FramePadding.y.
    ImVec2      DisplayWindowPadding;       // Apply to regular windows: amount which we enforce to keep visible when moving near edges of your screen.
    ImVec2      DisplaySafeAreaPadding;     // Apply to every windows, menus, popups, tooltips: amount where we avoid displaying contents. Adjust if you cannot see the edges of your screen (e.g. on a TV where scaling has not been configured).
+    float       DockingSeparatorSize;       // Thickness of resizing border between docked windows
    float       MouseCursorScale;           // Scale software rendered mouse cursor (when io.MouseDrawCursor is enabled). We apply per-monitor DPI scaling over this scale. May be removed later.
    bool        AntiAliasedLines;           // Enable anti-aliased lines/borders. Disable if you are really tight on CPU/GPU. Latched at the beginning of the frame (copied to ImDrawList).
    bool        AntiAliasedLinesUseTex;     // Enable anti-aliased lines/borders using textures where possible. Require backend to render with bilinear filtering (NOT point/nearest filtering). Latched at the beginning of the frame (copied to ImDrawList).
@@ -2232,6 +2310,18 @@ struct ImGuiIO
    bool        ConfigNavCursorVisibleAuto;     // = true           // Using directional navigation key makes the cursor visible. Mouse click hides the cursor.
    bool        ConfigNavCursorVisibleAlways;   // = false          // Navigation cursor is always visible.

+    // Docking options (when ImGuiConfigFlags_DockingEnable is set)
+    bool        ConfigDockingNoSplit;           // = false          // Simplified docking mode: disable window splitting, so docking is limited to merging multiple windows together into tab-bars.
+    bool        ConfigDockingWithShift;         // = false          // Enable docking with holding Shift key (reduce visual noise, allows dropping in wider space)
+    bool        ConfigDockingAlwaysTabBar;      // = false          // [BETA] [FIXME: This currently creates regression with auto-sizing and general overhead] Make every single floating window display within a docking node.
+    bool        ConfigDockingTransparentPayload;// = false          // [BETA] Make window or viewport transparent when docking and only display docking boxes on the target viewport. Useful if rendering of multiple viewport cannot be synced. Best used with ConfigViewportsNoAutoMerge.
+
+    // Viewport options (when ImGuiConfigFlags_ViewportsEnable is set)
+    bool        ConfigViewportsNoAutoMerge;     // = false;         // Set to make all floating imgui windows always create their own viewport. Otherwise, they are merged into the main host viewports when overlapping it. May also set ImGuiViewportFlags_NoAutoMerge on individual viewport.
+    bool        ConfigViewportsNoTaskBarIcon;   // = false          // Disable default OS task bar icon flag for secondary viewports. When a viewport doesn't want a task bar icon, ImGuiViewportFlags_NoTaskBarIcon will be set on it.
+    bool        ConfigViewportsNoDecoration;    // = true           // Disable default OS window decoration flag for secondary viewports. When a viewport doesn't want window decorations, ImGuiViewportFlags_NoDecoration will be set on it. Enabling decoration can create subsequent issues at OS levels (e.g. minimum window size).
+    bool        ConfigViewportsNoDefaultParent; // = false          // Disable default OS parenting to main viewport for secondary viewports. By default, viewports are marked with ParentViewportId = <main_viewport>, expecting the platform backend to setup a parent/child relationship between the OS windows (some backend may ignore this). Set to true if you want the default to be 0, then all viewports will be top-level OS windows.
+
    // Miscellaneous options
    // (you can visualize and interact with all options in 'Demo->Configuration')
    bool        MouseDrawCursor;                // = false          // Request ImGui to draw a mouse cursor for you (if you are on a platform without a mouse cursor). Cannot be easily renamed to 'io.ConfigXXX' because this is frequently used by backend implementations.
@@ -2327,6 +2417,7 @@ struct ImGuiIO
    IMGUI_API void  AddMouseButtonEvent(int button, bool down);             // Queue a mouse button change
    IMGUI_API void  AddMouseWheelEvent(float wheel_x, float wheel_y);       // Queue a mouse wheel update. wheel_y<0: scroll down, wheel_y>0: scroll up, wheel_x<0: scroll right, wheel_x>0: scroll left.
    IMGUI_API void  AddMouseSourceEvent(ImGuiMouseSource source);           // Queue a mouse source change (Mouse/TouchScreen/Pen)
+    IMGUI_API void  AddMouseViewportEvent(ImGuiID id);                      // Queue a mouse hovered viewport. Requires backend to set ImGuiBackendFlags_HasMouseHoveredViewport to call this (for multi-viewport support).
    IMGUI_API void  AddFocusEvent(bool focused);                            // Queue a gain/loss of focus for the application (generally based on OS/platform focus of your window)
    IMGUI_API void  AddInputCharacter(unsigned int c);                      // Queue a new character input
    IMGUI_API void  AddInputCharacterUTF16(ImWchar16 c);                    // Queue a new character input from a UTF-16 character, it can be a surrogate
@@ -2375,6 +2466,7 @@ struct ImGuiIO
    float       MouseWheel;                         // Mouse wheel Vertical: 1 unit scrolls about 5 lines text. >0 scrolls Up, <0 scrolls Down. Hold SHIFT to turn vertical scroll into horizontal scroll.
    float       MouseWheelH;                        // Mouse wheel Horizontal. >0 scrolls Left, <0 scrolls Right. Most users don't have a mouse with a horizontal wheel, may not be filled by all backends.
    ImGuiMouseSource MouseSource;                   // Mouse actual input peripheral (Mouse/TouchScreen/Pen).
+    ImGuiID     MouseHoveredViewport;               // (Optional) Modify using io.AddMouseViewportEvent(). With multi-viewports: viewport the OS mouse is hovering. If possible _IGNORING_ viewports with the ImGuiViewportFlags_NoInputs flag is much better (few backends can handle that). Set io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport if you can provide this info. If you don't imgui will infer the value using the rectangles and last focused time of the viewports it knows about (ignoring other OS windows).
    bool        KeyCtrl;                            // Keyboard modifier down: Control
    bool        KeyShift;                           // Keyboard modifier down: Shift
    bool        KeyAlt;                             // Keyboard modifier down: Alt
@@ -2398,6 +2490,7 @@ struct ImGuiIO
    bool        MouseCtrlLeftAsRightClick;          // (OSX) Set to true when the current click was a ctrl-click that spawned a simulated right click
    float       MouseDownDuration[5];               // Duration the mouse button has been down (0.0f == just clicked)
    float       MouseDownDurationPrev[5];           // Previous time the mouse button has been down
+    ImVec2      MouseDragMaxDistanceAbs[5];         // Maximum distance, absolute, on each axis, of how much mouse has traveled from the clicking point
    float       MouseDragMaxDistanceSqr[5];         // Squared maximum distance of how much mouse has traveled from the clicking point (used for moving thresholds)
    float       PenPressure;                        // Touch/Pen pressure (0.0f to 1.0f, should be >0.0f only when MouseDown[0] == true). Helper storage currently unused by Dear ImGui.
    bool        AppFocusLost;                       // Only modify via AddFocusEvent()
@@ -2481,6 +2574,28 @@ struct ImGuiSizeCallbackData
    ImVec2  DesiredSize;    // Read-write.  Desired size, based on user's mouse position. Write to this field to restrain resizing.
 };

+// [ALPHA] Rarely used / very advanced uses only. Use with SetNextWindowClass() and DockSpace() functions.
+// Important: the content of this class is still highly WIP and likely to change and be refactored
+// before we stabilize Docking features. Please be mindful if using this.
+// Provide hints:
+// - To the platform backend via altered viewport flags (enable/disable OS decoration, OS task bar icons, etc.)
+// - To the platform backend for OS level parent/child relationships of viewport.
+// - To the docking system for various options and filtering.
+struct ImGuiWindowClass
+{
+    ImGuiID             ClassId;                    // User data. 0 = Default class (unclassed). Windows of different classes cannot be docked with each others.
+    ImGuiID             ParentViewportId;           // Hint for the platform backend. -1: use default. 0: request platform backend to not parent the platform. != 0: request platform backend to create a parent<>child relationship between the platform windows. Not conforming backends are free to e.g. parent every viewport to the main viewport or not.
+    ImGuiID             FocusRouteParentWindowId;   // ID of parent window for shortcut focus route evaluation, e.g. Shortcut() call from Parent Window will succeed when this window is focused.
+    ImGuiViewportFlags  ViewportFlagsOverrideSet;   // Viewport flags to set when a window of this class owns a viewport. This allows you to enforce OS decoration or task bar icon, override the defaults on a per-window basis.
+    ImGuiViewportFlags  ViewportFlagsOverrideClear; // Viewport flags to clear when a window of this class owns a viewport. This allows you to enforce OS decoration or task bar icon, override the defaults on a per-window basis.
+    ImGuiTabItemFlags   TabItemFlagsOverrideSet;    // [EXPERIMENTAL] TabItem flags to set when a window of this class gets submitted into a dock node tab bar. May use with ImGuiTabItemFlags_Leading or ImGuiTabItemFlags_Trailing.
+    ImGuiDockNodeFlags  DockNodeFlagsOverrideSet;   // [EXPERIMENTAL] Dock node flags to set when a window of this class is hosted by a dock node (it doesn't have to be selected!)
+    bool                DockingAlwaysTabBar;        // Set to true to enforce single floating windows of this class always having their own docking node (equivalent of setting the global io.ConfigDockingAlwaysTabBar)
+    bool                DockingAllowUnclassed;      // Set to true to allow windows of this class to be docked/merged with an unclassed window. // FIXME-DOCK: Move to DockNodeFlags override?
+
+    ImGuiWindowClass() { memset(this, 0, sizeof(*this)); ParentViewportId = (ImGuiID)-1; DockingAllowUnclassed = true; }
+};
+
 // Data payload for Drag and Drop operations: AcceptDragDropPayload(), GetDragDropPayload()
 struct ImGuiPayload
 {
@@ -3197,7 +3312,7 @@ struct ImDrawList
 struct ImDrawData
 {
    bool                Valid;              // Only valid after Render() is called and before the next NewFrame() is called.
-    int                 CmdListsCount;      // Number of ImDrawList* to render (should always be == CmdLists.size)
+    int                 CmdListsCount;      // Number of ImDrawList* to render
    int                 TotalIdxCount;      // For convenience, sum of all ImDrawList's IdxBuffer.Size
    int                 TotalVtxCount;      // For convenience, sum of all ImDrawList's VtxBuffer.Size
    ImVector<ImDrawList*> CmdLists;         // Array of ImDrawList* to render. The ImDrawLists are owned by ImGuiContext and only pointed to from here.
@@ -3481,11 +3596,24 @@ enum ImGuiViewportFlags_
    ImGuiViewportFlags_None                     = 0,
    ImGuiViewportFlags_IsPlatformWindow         = 1 << 0,   // Represent a Platform Window
    ImGuiViewportFlags_IsPlatformMonitor        = 1 << 1,   // Represent a Platform Monitor (unused yet)
-    ImGuiViewportFlags_OwnedByApp               = 1 << 2,   // Platform Window: Is created/managed by the application (rather than a dear imgui backend)
+    ImGuiViewportFlags_OwnedByApp               = 1 << 2,   // Platform Window: Is created/managed by the user application? (rather than our backend)
+    ImGuiViewportFlags_NoDecoration             = 1 << 3,   // Platform Window: Disable platform decorations: title bar, borders, etc. (generally set all windows, but if ImGuiConfigFlags_ViewportsDecoration is set we only set this on popups/tooltips)
+    ImGuiViewportFlags_NoTaskBarIcon            = 1 << 4,   // Platform Window: Disable platform task bar icon (generally set on popups/tooltips, or all windows if ImGuiConfigFlags_ViewportsNoTaskBarIcon is set)
+    ImGuiViewportFlags_NoFocusOnAppearing       = 1 << 5,   // Platform Window: Don't take focus when created.
+    ImGuiViewportFlags_NoFocusOnClick           = 1 << 6,   // Platform Window: Don't take focus when clicked on.
+    ImGuiViewportFlags_NoInputs                 = 1 << 7,   // Platform Window: Make mouse pass through so we can drag this window while peaking behind it.
+    ImGuiViewportFlags_NoRendererClear          = 1 << 8,   // Platform Window: Renderer doesn't need to clear the framebuffer ahead (because we will fill it entirely).
+    ImGuiViewportFlags_NoAutoMerge              = 1 << 9,   // Platform Window: Avoid merging this window into another host window. This can only be set via ImGuiWindowClass viewport flags override (because we need to now ahead if we are going to create a viewport in the first place!).
+    ImGuiViewportFlags_TopMost                  = 1 << 10,  // Platform Window: Display on top (for tooltips only).
+    ImGuiViewportFlags_CanHostOtherWindows      = 1 << 11,  // Viewport can host multiple imgui windows (secondary viewports are associated to a single window). // FIXME: In practice there's still probably code making the assumption that this is always and only on the MainViewport. Will fix once we add support for "no main viewport".
+
+    // Output status flags (from Platform)
+    ImGuiViewportFlags_IsMinimized              = 1 << 12,  // Platform Window: Window is minimized, can skip render. When minimized we tend to avoid using the viewport pos/size for clipping window or testing if they are contained in the viewport.
+    ImGuiViewportFlags_IsFocused                = 1 << 13,  // Platform Window: Window is focused (last call to Platform_GetWindowFocus() returned true)
 };

 // - Currently represents the Platform Window created by the application which is hosting our Dear ImGui windows.
-// - In 'docking' branch with multi-viewport enabled, we extend this concept to have multiple active viewports.
+// - With multi-viewport enabled, we extend this concept to have multiple active viewports.
 // - In the future we will extend this concept further to also represent Platform Monitor and support a "no main platform window" operation mode.
 // - About Main Area vs Work Area:
 //   - Main Area = entire viewport.
@@ -3499,12 +3627,26 @@ struct ImGuiViewport
    ImVec2              Size;                   // Main Area: Size of the viewport.
    ImVec2              WorkPos;                // Work Area: Position of the viewport minus task bars, menus bars, status bars (>= Pos)
    ImVec2              WorkSize;               // Work Area: Size of the viewport minus task bars, menu bars, status bars (<= Size)
+    float               DpiScale;               // 1.0f = 96 DPI = No extra scale.
+    ImGuiID             ParentViewportId;       // (Advanced) 0: no parent. Instruct the platform backend to setup a parent/child relationship between platform windows.
+    ImDrawData*         DrawData;               // The ImDrawData corresponding to this viewport. Valid after Render() and until the next call to NewFrame().

    // Platform/Backend Dependent Data
-    void*               PlatformHandle;         // void* to hold higher-level, platform window handle (e.g. HWND, GLFWWindow*, SDL_Window*)
-    void*               PlatformHandleRaw;      // void* to hold lower-level, platform-native window handle (under Win32 this is expected to be a HWND, unused for other platforms)
+    // Our design separate the Renderer and Platform backends to facilitate combining default backends with each others.
+    // When our create your own backend for a custom engine, it is possible that both Renderer and Platform will be handled
+    // by the same system and you may not need to use all the UserData/Handle fields.
+    // The library never uses those fields, they are merely storage to facilitate backend implementation.
+    void*               RendererUserData;       // void* to hold custom data structure for the renderer (e.g. swap chain, framebuffers etc.). generally set by your Renderer_CreateWindow function.
+    void*               PlatformUserData;       // void* to hold custom data structure for the OS / platform (e.g. windowing info, render context). generally set by your Platform_CreateWindow function.
+    void*               PlatformHandle;         // void* to hold higher-level, platform window handle (e.g. HWND, GLFWWindow*, SDL_Window*), for FindViewportByPlatformHandle().
+    void*               PlatformHandleRaw;      // void* to hold lower-level, platform-native window handle (under Win32 this is expected to be a HWND, unused for other platforms), when using an abstraction layer like GLFW or SDL (where PlatformHandle would be a SDL_Window*)
+    bool                PlatformWindowCreated;  // Platform window has been created (Platform_CreateWindow() has been called). This is false during the first frame where a viewport is being created.
+    bool                PlatformRequestMove;    // Platform window requested move (e.g. window was moved by the OS / host window manager, authoritative position will be OS window position)
+    bool                PlatformRequestResize;  // Platform window requested resize (e.g. window was resized by the OS / host window manager, authoritative size will be OS window size)
+    bool                PlatformRequestClose;   // Platform window requested closure (e.g. window was moved by the OS / host window manager, e.g. pressing ALT-F4)

    ImGuiViewport()     { memset(this, 0, sizeof(*this)); }
+    ~ImGuiViewport()    { IM_ASSERT(PlatformUserData == NULL && RendererUserData == NULL); }

    // Helpers
    ImVec2              GetCenter() const       { return ImVec2(Pos.x + Size.x * 0.5f, Pos.y + Size.y * 0.5f); }
@@ -3512,7 +3654,53 @@ struct ImGuiViewport
 };

 //-----------------------------------------------------------------------------
-// [SECTION] Platform Dependent Interfaces
+// [SECTION] ImGuiPlatformIO + other Platform Dependent Interfaces (ImGuiPlatformMonitor, ImGuiPlatformImeData)
+//-----------------------------------------------------------------------------
+
+// [BETA] (Optional) Multi-Viewport Support!
+// If you are new to Dear ImGui and trying to integrate it into your engine, you can probably ignore this for now.
+//
+// This feature allows you to seamlessly drag Dear ImGui windows outside of your application viewport.
+// This is achieved by creating new Platform/OS windows on the fly, and rendering into them.
+// Dear ImGui manages the viewport structures, and the backend create and maintain one Platform/OS window for each of those viewports.
+//
+// See Recap:   https://github.com/ocornut/imgui/wiki/Multi-Viewports
+// See Glossary https://github.com/ocornut/imgui/wiki/Glossary for details about some of the terminology.
+//
+// About the coordinates system:
+// - When multi-viewports are enabled, all Dear ImGui coordinates become absolute coordinates (same as OS coordinates!)
+// - So e.g. ImGui::SetNextWindowPos(ImVec2(0,0)) will position a window relative to your primary monitor!
+// - If you want to position windows relative to your main application viewport, use ImGui::GetMainViewport()->Pos as a base position.
+//
+// Steps to use multi-viewports in your application, when using a default backend from the examples/ folder:
+// - Application:  Enable feature with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+// - Backend:      The backend initialization will setup all necessary ImGuiPlatformIO's functions and update monitors info every frame.
+// - Application:  In your main loop, call ImGui::UpdatePlatformWindows(), ImGui::RenderPlatformWindowsDefault() after EndFrame() or Render().
+// - Application:  Fix absolute coordinates used in ImGui::SetWindowPos() or ImGui::SetNextWindowPos() calls.
+//
+// Steps to use multi-viewports in your application, when using a custom backend:
+// - Important:    THIS IS NOT EASY TO DO and comes with many subtleties not described here!
+//                 It's also an experimental feature, so some of the requirements may evolve.
+//                 Consider using default backends if you can. Either way, carefully follow and refer to examples/ backends for details.
+// - Application:  Enable feature with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+// - Backend:      Hook ImGuiPlatformIO's Platform_* and Renderer_* callbacks (see below).
+//                 Set 'io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports' and 'io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports'.
+//                 Update ImGuiPlatformIO's Monitors list every frame.
+//                 Update MousePos every frame, in absolute coordinates.
+// - Application:  In your main loop, call ImGui::UpdatePlatformWindows(), ImGui::RenderPlatformWindowsDefault() after EndFrame() or Render().
+//                 You may skip calling RenderPlatformWindowsDefault() if its API is not convenient for your needs. Read comments below.
+// - Application:  Fix absolute coordinates used in ImGui::SetWindowPos() or ImGui::SetNextWindowPos() calls.
+//
+// About ImGui::RenderPlatformWindowsDefault():
+// - This function is a mostly a _helper_ for the common-most cases, and to facilitate using default backends.
+// - You can check its simple source code to understand what it does.
+//   It basically iterates secondary viewports and call 4 functions that are setup in ImGuiPlatformIO, if available:
+//     Platform_RenderWindow(), Renderer_RenderWindow(), Platform_SwapBuffers(), Renderer_SwapBuffers()
+//   Those functions pointers exists only for the benefit of RenderPlatformWindowsDefault().
+// - If you have very specific rendering needs (e.g. flipping multiple swap-chain simultaneously, unusual sync/threading issues, etc.),
+//   you may be tempted to ignore RenderPlatformWindowsDefault() and write customized code to perform your renderingg.
+//   You may decide to setup the platform_io's *RenderWindow and *SwapBuffers pointers and call your functions through those pointers,
+//   or you may decide to never setup those pointers and call your code directly. They are a convenience, not an obligatory interface.
 //-----------------------------------------------------------------------------

 // Access via ImGui::GetPlatformIO()
@@ -3521,7 +3709,7 @@ struct ImGuiPlatformIO
    IMGUI_API ImGuiPlatformIO();

    //------------------------------------------------------------------
-    // Interface with OS and Platform backend
+    // Interface with OS and Platform backend (basic)
    //------------------------------------------------------------------

    // Optional: Access OS clipboard
@@ -3551,6 +3739,74 @@ struct ImGuiPlatformIO

    // Written by some backends during ImGui_ImplXXXX_RenderDrawData() call to point backend_specific ImGui_ImplXXXX_RenderState* structure.
    void*       Renderer_RenderState;
+
+    //------------------------------------------------------------------
+    // Input - Interface with OS/backends (Multi-Viewport support!)
+    //------------------------------------------------------------------
+
+    // For reference, the second column shows which function are generally calling the Platform Functions:
+    //   N = ImGui::NewFrame()                        ~ beginning of the dear imgui frame: read info from platform/OS windows (latest size/position)
+    //   F = ImGui::Begin(), ImGui::EndFrame()        ~ during the dear imgui frame
+    //   U = ImGui::UpdatePlatformWindows()           ~ after the dear imgui frame: create and update all platform/OS windows
+    //   R = ImGui::RenderPlatformWindowsDefault()    ~ render
+    //   D = ImGui::DestroyPlatformWindows()          ~ shutdown
+    // The general idea is that NewFrame() we will read the current Platform/OS state, and UpdatePlatformWindows() will write to it.
+
+    // The handlers are designed so we can mix and match two imgui_impl_xxxx files, one Platform backend and one Renderer backend.
+    // Custom engine backends will often provide both Platform and Renderer interfaces together and so may not need to use all functions.
+    // Platform functions are typically called _before_ their Renderer counterpart, apart from Destroy which are called the other way.
+
+    // Platform Backend functions (e.g. Win32, GLFW, SDL) ------------------- Called by -----
+    void    (*Platform_CreateWindow)(ImGuiViewport* vp);                    // . . U . .  // Create a new platform window for the given viewport
+    void    (*Platform_DestroyWindow)(ImGuiViewport* vp);                   // N . U . D  //
+    void    (*Platform_ShowWindow)(ImGuiViewport* vp);                      // . . U . .  // Newly created windows are initially hidden so SetWindowPos/Size/Title can be called on them before showing the window
+    void    (*Platform_SetWindowPos)(ImGuiViewport* vp, ImVec2 pos);        // . . U . .  // Set platform window position (given the upper-left corner of client area)
+    ImVec2  (*Platform_GetWindowPos)(ImGuiViewport* vp);                    // N . . . .  //
+    void    (*Platform_SetWindowSize)(ImGuiViewport* vp, ImVec2 size);      // . . U . .  // Set platform window client area size (ignoring OS decorations such as OS title bar etc.)
+    ImVec2  (*Platform_GetWindowSize)(ImGuiViewport* vp);                   // N . . . .  // Get platform window client area size
+    void    (*Platform_SetWindowFocus)(ImGuiViewport* vp);                  // N . . . .  // Move window to front and set input focus
+    bool    (*Platform_GetWindowFocus)(ImGuiViewport* vp);                  // . . U . .  //
+    bool    (*Platform_GetWindowMinimized)(ImGuiViewport* vp);              // N . . . .  // Get platform window minimized state. When minimized, we generally won't attempt to get/set size and contents will be culled more easily
+    void    (*Platform_SetWindowTitle)(ImGuiViewport* vp, const char* str); // . . U . .  // Set platform window title (given an UTF-8 string)
+    void    (*Platform_SetWindowAlpha)(ImGuiViewport* vp, float alpha);     // . . U . .  // (Optional) Setup global transparency (not per-pixel transparency)
+    void    (*Platform_UpdateWindow)(ImGuiViewport* vp);                    // . . U . .  // (Optional) Called by UpdatePlatformWindows(). Optional hook to allow the platform backend from doing general book-keeping every frame.
+    void    (*Platform_RenderWindow)(ImGuiViewport* vp, void* render_arg);  // . . . R .  // (Optional) Main rendering (platform side! This is often unused, or just setting a "current" context for OpenGL bindings). 'render_arg' is the value passed to RenderPlatformWindowsDefault().
+    void    (*Platform_SwapBuffers)(ImGuiViewport* vp, void* render_arg);   // . . . R .  // (Optional) Call Present/SwapBuffers (platform side! This is often unused!). 'render_arg' is the value passed to RenderPlatformWindowsDefault().
+    float   (*Platform_GetWindowDpiScale)(ImGuiViewport* vp);               // N . . . .  // (Optional) [BETA] FIXME-DPI: DPI handling: Return DPI scale for this viewport. 1.0f = 96 DPI.
+    void    (*Platform_OnChangedViewport)(ImGuiViewport* vp);               // . F . . .  // (Optional) [BETA] FIXME-DPI: DPI handling: Called during Begin() every time the viewport we are outputting into changes, so backend has a chance to swap fonts to adjust style.
+    ImVec4  (*Platform_GetWindowWorkAreaInsets)(ImGuiViewport* vp);         // N . . . .  // (Optional) [BETA] Get initial work area inset for the viewport (won't be covered by main menu bar, dockspace over viewport etc.). Default to (0,0),(0,0). 'safeAreaInsets' in iOS land, 'DisplayCutout' in Android land.
+    int     (*Platform_CreateVkSurface)(ImGuiViewport* vp, ImU64 vk_inst, const void* vk_allocators, ImU64* out_vk_surface); // (Optional) For a Vulkan Renderer to call into Platform code (since the surface creation needs to tie them both).
+
+    // Renderer Backend functions (e.g. DirectX, OpenGL, Vulkan) ------------ Called by -----
+    void    (*Renderer_CreateWindow)(ImGuiViewport* vp);                    // . . U . .  // Create swap chain, frame buffers etc. (called after Platform_CreateWindow)
+    void    (*Renderer_DestroyWindow)(ImGuiViewport* vp);                   // N . U . D  // Destroy swap chain, frame buffers etc. (called before Platform_DestroyWindow)
+    void    (*Renderer_SetWindowSize)(ImGuiViewport* vp, ImVec2 size);      // . . U . .  // Resize swap chain, frame buffers etc. (called after Platform_SetWindowSize)
+    void    (*Renderer_RenderWindow)(ImGuiViewport* vp, void* render_arg);  // . . . R .  // (Optional) Clear framebuffer, setup render target, then render the viewport->DrawData. 'render_arg' is the value passed to RenderPlatformWindowsDefault().
+    void    (*Renderer_SwapBuffers)(ImGuiViewport* vp, void* render_arg);   // . . . R .  // (Optional) Call Present/SwapBuffers. 'render_arg' is the value passed to RenderPlatformWindowsDefault().
+
+    // (Optional) Monitor list
+    // - Updated by: app/backend. Update every frame to dynamically support changing monitor or DPI configuration.
+    // - Used by: dear imgui to query DPI info, clamp popups/tooltips within same monitor and not have them straddle monitors.
+    ImVector<ImGuiPlatformMonitor>  Monitors;
+
+    //------------------------------------------------------------------
+    // Output - List of viewports to render into platform windows
+    //------------------------------------------------------------------
+
+    // Viewports list (the list is updated by calling ImGui::EndFrame or ImGui::Render)
+    // (in the future we will attempt to organize this feature to remove the need for a "main viewport")
+    ImVector<ImGuiViewport*>        Viewports;                              // Main viewports, followed by all secondary viewports.
+};
+
+// (Optional) This is required when enabling multi-viewport. Represent the bounds of each connected monitor/display and their DPI.
+// We use this information for multiple DPI support + clamping the position of popups and tooltips so they don't straddle multiple monitors.
+struct ImGuiPlatformMonitor
+{
+    ImVec2  MainPos, MainSize;      // Coordinates of the area displayed on this monitor (Min = upper left, Max = bottom right)
+    ImVec2  WorkPos, WorkSize;      // Coordinates without task bars / side bars / menu bars. Used to avoid positioning popups/tooltips inside this region. If you don't have this info, please copy the value for MainPos/MainSize.
+    float   DpiScale;               // 1.0f = 96 DPI
+    void*   PlatformHandle;         // Backend dependant data (e.g. HMONITOR, GLFWmonitor*, SDL Display Index, NSScreen*)
+    ImGuiPlatformMonitor()          { MainPos = MainSize = WorkPos = WorkSize = ImVec2(0, 0); DpiScale = 1.0f; PlatformHandle = NULL; }
 };

 // (Optional) Support for IME (Input Method Editor) via the platform_io.Platform_SetImeDataFn() function.
@@ -94,6 +94,7 @@ Index of this file:
 // [SECTION] Example App: Fullscreen window / ShowExampleAppFullscreen()
 // [SECTION] Example App: Manipulating window titles / ShowExampleAppWindowTitles()
 // [SECTION] Example App: Custom Rendering using ImDrawList API / ShowExampleAppCustomRendering()
+// [SECTION] Example App: Docking, DockSpace / ShowExampleAppDockSpace()
 // [SECTION] Example App: Documents Handling / ShowExampleAppDocuments()
 // [SECTION] Example App: Assets Browser / ShowExampleAppAssetsBrowser()

@@ -207,6 +208,7 @@ static void ShowExampleAppMainMenuBar();
 static void ShowExampleAppAssetsBrowser(bool* p_open);
 static void ShowExampleAppConsole(bool* p_open);
 static void ShowExampleAppCustomRendering(bool* p_open);
+static void ShowExampleAppDockSpace(bool* p_open);
 static void ShowExampleAppDocuments(bool* p_open);
 static void ShowExampleAppLog(bool* p_open);
 static void ShowExampleAppLayout(bool* p_open);
@@ -248,6 +250,16 @@ static void HelpMarker(const char* desc)
    }
 }

+static void ShowDockingDisabledMessage()
+{
+    ImGuiIO& io = ImGui::GetIO();
+    ImGui::Text("ERROR: Docking is not enabled! See Demo > Configuration.");
+    ImGui::Text("Set io.ConfigFlags |= ImGuiConfigFlags_DockingEnable in your code, or ");
+    ImGui::SameLine(0.0f, 0.0f);
+    if (ImGui::SmallButton("click here"))
+        io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
+}
+
 // Helper to wire demo markers located in code to an interactive browser
 typedef void (*ImGuiDemoMarkerCallback)(const char* file, int line, const char* section, void* user_data);
 extern ImGuiDemoMarkerCallback      GImGuiDemoMarkerCallback;
@@ -352,6 +364,7 @@ struct ImGuiDemoWindowData
    bool ShowAppConsole = false;
    bool ShowAppCustomRendering = false;
    bool ShowAppDocuments = false;
+    bool ShowAppDockSpace = false;
    bool ShowAppLog = false;
    bool ShowAppLayout = false;
    bool ShowAppPropertyEditor = false;
@@ -390,7 +403,8 @@ void ImGui::ShowDemoWindow(bool* p_open)

    // Examples Apps (accessible from the "Examples" menu)
    if (demo_data.ShowMainMenuBar)          { ShowExampleAppMainMenuBar(); }
-    if (demo_data.ShowAppDocuments)         { ShowExampleAppDocuments(&demo_data.ShowAppDocuments); }
+    if (demo_data.ShowAppDockSpace)         { ShowExampleAppDockSpace(&demo_data.ShowAppDockSpace); } // Important: Process the Docking app first, as explicit DockSpace() nodes needs to be submitted early (read comments near the DockSpace function)
+    if (demo_data.ShowAppDocuments)         { ShowExampleAppDocuments(&demo_data.ShowAppDocuments); } // ...process the Document app next, as it may also use a DockSpace()
    if (demo_data.ShowAppAssetsBrowser)     { ShowExampleAppAssetsBrowser(&demo_data.ShowAppAssetsBrowser); }
    if (demo_data.ShowAppConsole)           { ShowExampleAppConsole(&demo_data.ShowAppConsole); }
    if (demo_data.ShowAppCustomRendering)   { ShowExampleAppCustomRendering(&demo_data.ShowAppCustomRendering); }
@@ -427,6 +441,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
    static bool no_nav = false;
    static bool no_background = false;
    static bool no_bring_to_front = false;
+    static bool no_docking = false;
    static bool unsaved_document = false;

    ImGuiWindowFlags window_flags = 0;
@@ -439,6 +454,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
    if (no_nav)             window_flags |= ImGuiWindowFlags_NoNav;
    if (no_background)      window_flags |= ImGuiWindowFlags_NoBackground;
    if (no_bring_to_front)  window_flags |= ImGuiWindowFlags_NoBringToFrontOnFocus;
+    if (no_docking)         window_flags |= ImGuiWindowFlags_NoDocking;
    if (unsaved_document)   window_flags |= ImGuiWindowFlags_UnsavedDocument;
    if (no_close)           p_open = NULL; // Don't pass our bool* to Begin

@@ -541,6 +557,44 @@ void ImGui::ShowDemoWindow(bool* p_open)
            ImGui::Checkbox("io.ConfigNavCursorVisibleAlways", &io.ConfigNavCursorVisibleAlways);
            ImGui::SameLine(); HelpMarker("Navigation cursor is always visible.");

+            ImGui::SeparatorText("Docking");
+            ImGui::CheckboxFlags("io.ConfigFlags: DockingEnable", &io.ConfigFlags, ImGuiConfigFlags_DockingEnable);
+            ImGui::SameLine();
+            if (io.ConfigDockingWithShift)
+                HelpMarker("Drag from window title bar or their tab to dock/undock. Hold SHIFT to enable docking.\n\nDrag from window menu button (upper-left button) to undock an entire node (all windows).");
+            else
+                HelpMarker("Drag from window title bar or their tab to dock/undock. Hold SHIFT to disable docking.\n\nDrag from window menu button (upper-left button) to undock an entire node (all windows).");
+            if (io.ConfigFlags & ImGuiConfigFlags_DockingEnable)
+            {
+                ImGui::Indent();
+                ImGui::Checkbox("io.ConfigDockingNoSplit", &io.ConfigDockingNoSplit);
+                ImGui::SameLine(); HelpMarker("Simplified docking mode: disable window splitting, so docking is limited to merging multiple windows together into tab-bars.");
+                ImGui::Checkbox("io.ConfigDockingWithShift", &io.ConfigDockingWithShift);
+                ImGui::SameLine(); HelpMarker("Enable docking when holding Shift only (allow to drop in wider space, reduce visual noise)");
+                ImGui::Checkbox("io.ConfigDockingAlwaysTabBar", &io.ConfigDockingAlwaysTabBar);
+                ImGui::SameLine(); HelpMarker("Create a docking node and tab-bar on single floating windows.");
+                ImGui::Checkbox("io.ConfigDockingTransparentPayload", &io.ConfigDockingTransparentPayload);
+                ImGui::SameLine(); HelpMarker("Make window or viewport transparent when docking and only display docking boxes on the target viewport. Useful if rendering of multiple viewport cannot be synced. Best used with ConfigViewportsNoAutoMerge.");
+                ImGui::Unindent();
+            }
+
+            ImGui::SeparatorText("Multi-viewports");
+            ImGui::CheckboxFlags("io.ConfigFlags: ViewportsEnable", &io.ConfigFlags, ImGuiConfigFlags_ViewportsEnable);
+            ImGui::SameLine(); HelpMarker("[beta] Enable beta multi-viewports support. See ImGuiPlatformIO for details.");
+            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+            {
+                ImGui::Indent();
+                ImGui::Checkbox("io.ConfigViewportsNoAutoMerge", &io.ConfigViewportsNoAutoMerge);
+                ImGui::SameLine(); HelpMarker("Set to make all floating imgui windows always create their own viewport. Otherwise, they are merged into the main host viewports when overlapping it.");
+                ImGui::Checkbox("io.ConfigViewportsNoTaskBarIcon", &io.ConfigViewportsNoTaskBarIcon);
+                ImGui::SameLine(); HelpMarker("Toggling this at runtime is normally unsupported (most platform backends won't refresh the task bar icon state right away).");
+                ImGui::Checkbox("io.ConfigViewportsNoDecoration", &io.ConfigViewportsNoDecoration);
+                ImGui::SameLine(); HelpMarker("Toggling this at runtime is normally unsupported (most platform backends won't refresh the decoration right away).");
+                ImGui::Checkbox("io.ConfigViewportsNoDefaultParent", &io.ConfigViewportsNoDefaultParent);
+                ImGui::SameLine(); HelpMarker("Toggling this at runtime is normally unsupported (most platform backends won't refresh the parenting right away).");
+                ImGui::Unindent();
+            }
+
            ImGui::SeparatorText("Windows");
            ImGui::Checkbox("io.ConfigWindowsResizeFromEdges", &io.ConfigWindowsResizeFromEdges);
            ImGui::SameLine(); HelpMarker("Enable resizing of windows from their edges and from the lower-left corner.\nThis requires ImGuiBackendFlags_HasMouseCursors for better mouse cursor feedback.");
@@ -606,12 +660,16 @@ void ImGui::ShowDemoWindow(bool* p_open)
                "Those flags are set by the backends (imgui_impl_xxx files) to specify their capabilities.\n"
                "Here we expose them as read-only fields to avoid breaking interactions with your backend.");

+            // Make a local copy to avoid modifying actual backend flags.
            // FIXME: Maybe we need a BeginReadonly() equivalent to keep label bright?
            ImGui::BeginDisabled();
-            ImGui::CheckboxFlags("io.BackendFlags: HasGamepad",           &io.BackendFlags, ImGuiBackendFlags_HasGamepad);
-            ImGui::CheckboxFlags("io.BackendFlags: HasMouseCursors",      &io.BackendFlags, ImGuiBackendFlags_HasMouseCursors);
-            ImGui::CheckboxFlags("io.BackendFlags: HasSetMousePos",       &io.BackendFlags, ImGuiBackendFlags_HasSetMousePos);
-            ImGui::CheckboxFlags("io.BackendFlags: RendererHasVtxOffset", &io.BackendFlags, ImGuiBackendFlags_RendererHasVtxOffset);
+            ImGui::CheckboxFlags("io.BackendFlags: HasGamepad",             &io.BackendFlags, ImGuiBackendFlags_HasGamepad);
+            ImGui::CheckboxFlags("io.BackendFlags: HasMouseCursors",        &io.BackendFlags, ImGuiBackendFlags_HasMouseCursors);
+            ImGui::CheckboxFlags("io.BackendFlags: HasSetMousePos",         &io.BackendFlags, ImGuiBackendFlags_HasSetMousePos);
+            ImGui::CheckboxFlags("io.BackendFlags: PlatformHasViewports",   &io.BackendFlags, ImGuiBackendFlags_PlatformHasViewports);
+            ImGui::CheckboxFlags("io.BackendFlags: HasMouseHoveredViewport",&io.BackendFlags, ImGuiBackendFlags_HasMouseHoveredViewport);
+            ImGui::CheckboxFlags("io.BackendFlags: RendererHasVtxOffset",   &io.BackendFlags, ImGuiBackendFlags_RendererHasVtxOffset);
+            ImGui::CheckboxFlags("io.BackendFlags: RendererHasViewports",   &io.BackendFlags, ImGuiBackendFlags_RendererHasViewports);
            ImGui::EndDisabled();

            ImGui::TreePop();
@@ -663,6 +721,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
            ImGui::TableNextColumn(); ImGui::Checkbox("No nav", &no_nav);
            ImGui::TableNextColumn(); ImGui::Checkbox("No background", &no_background);
            ImGui::TableNextColumn(); ImGui::Checkbox("No bring to front", &no_bring_to_front);
+            ImGui::TableNextColumn(); ImGui::Checkbox("No docking", &no_docking);
            ImGui::TableNextColumn(); ImGui::Checkbox("Unsaved document", &unsaved_document);
            ImGui::EndTable();
        }
@@ -705,6 +764,7 @@ static void ShowDemoWindowMenuBar(ImGuiDemoWindowData* demo_data)
            ImGui::MenuItem("Console", NULL, &demo_data->ShowAppConsole);
            ImGui::MenuItem("Custom rendering", NULL, &demo_data->ShowAppCustomRendering);
            ImGui::MenuItem("Documents", NULL, &demo_data->ShowAppDocuments);
+            ImGui::MenuItem("Dockspace", NULL, &demo_data->ShowAppDockSpace);
            ImGui::MenuItem("Log", NULL, &demo_data->ShowAppLog);
            ImGui::MenuItem("Property editor", NULL, &demo_data->ShowAppPropertyEditor);
            ImGui::MenuItem("Simple layout", NULL, &demo_data->ShowAppLayout);
@@ -2830,18 +2890,24 @@ static void ShowDemoWindowWidgets(ImGuiDemoWindowData* demo_data)
            "IsWindowFocused() = %d\n"
            "IsWindowFocused(_ChildWindows) = %d\n"
            "IsWindowFocused(_ChildWindows|_NoPopupHierarchy) = %d\n"
+            "IsWindowFocused(_ChildWindows|_DockHierarchy) = %d\n"
            "IsWindowFocused(_ChildWindows|_RootWindow) = %d\n"
            "IsWindowFocused(_ChildWindows|_RootWindow|_NoPopupHierarchy) = %d\n"
+            "IsWindowFocused(_ChildWindows|_RootWindow|_DockHierarchy) = %d\n"
            "IsWindowFocused(_RootWindow) = %d\n"
            "IsWindowFocused(_RootWindow|_NoPopupHierarchy) = %d\n"
+            "IsWindowFocused(_RootWindow|_DockHierarchy) = %d\n"
            "IsWindowFocused(_AnyWindow) = %d\n",
            ImGui::IsWindowFocused(),
            ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows),
            ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_NoPopupHierarchy),
+            ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_DockHierarchy),
            ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_RootWindow),
            ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_NoPopupHierarchy),
+            ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_DockHierarchy),
            ImGui::IsWindowFocused(ImGuiFocusedFlags_RootWindow),
            ImGui::IsWindowFocused(ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_NoPopupHierarchy),
+            ImGui::IsWindowFocused(ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_DockHierarchy),
            ImGui::IsWindowFocused(ImGuiFocusedFlags_AnyWindow));

        // Testing IsWindowHovered() function with its various flags.
@@ -2851,10 +2917,13 @@ static void ShowDemoWindowWidgets(ImGuiDemoWindowData* demo_data)
            "IsWindowHovered(_AllowWhenBlockedByActiveItem) = %d\n"
            "IsWindowHovered(_ChildWindows) = %d\n"
            "IsWindowHovered(_ChildWindows|_NoPopupHierarchy) = %d\n"
+            "IsWindowHovered(_ChildWindows|_DockHierarchy) = %d\n"
            "IsWindowHovered(_ChildWindows|_RootWindow) = %d\n"
            "IsWindowHovered(_ChildWindows|_RootWindow|_NoPopupHierarchy) = %d\n"
+            "IsWindowHovered(_ChildWindows|_RootWindow|_DockHierarchy) = %d\n"
            "IsWindowHovered(_RootWindow) = %d\n"
            "IsWindowHovered(_RootWindow|_NoPopupHierarchy) = %d\n"
+            "IsWindowHovered(_RootWindow|_DockHierarchy) = %d\n"
            "IsWindowHovered(_ChildWindows|_AllowWhenBlockedByPopup) = %d\n"
            "IsWindowHovered(_AnyWindow) = %d\n"
            "IsWindowHovered(_Stationary) = %d\n",
@@ -2863,10 +2932,13 @@ static void ShowDemoWindowWidgets(ImGuiDemoWindowData* demo_data)
            ImGui::IsWindowHovered(ImGuiHoveredFlags_AllowWhenBlockedByActiveItem),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_NoPopupHierarchy),
+            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_DockHierarchy),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_NoPopupHierarchy),
+            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_DockHierarchy),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_RootWindow),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_NoPopupHierarchy),
+            ImGui::IsWindowHovered(ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_DockHierarchy),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_AllowWhenBlockedByPopup),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_AnyWindow),
            ImGui::IsWindowHovered(ImGuiHoveredFlags_Stationary));
@@ -2879,10 +2951,13 @@ static void ShowDemoWindowWidgets(ImGuiDemoWindowData* demo_data)

        // Calling IsItemHovered() after begin returns the hovered status of the title bar.
        // This is useful in particular if you want to create a context menu associated to the title bar of a window.
+        // This will also work when docked into a Tab (the Tab replace the Title Bar and guarantee the same properties).
        static bool test_window = false;
        ImGui::Checkbox("Hovered/Active tests after Begin() for title bar testing", &test_window);
        if (test_window)
        {
+            // FIXME-DOCK: This window cannot be docked within the ImGui Demo window, this will cause a feedback loop and get them stuck.
+            // Could we fix this through an ImGuiWindowClass feature? Or an API call to tag our parent as "don't skip items"?
            ImGui::Begin("Title bar Hovered/Active tests", &test_window);
            if (ImGui::BeginPopupContextItem()) // <-- This is using IsItemHovered()
            {
@@ -7754,6 +7829,12 @@ void ImGui::ShowAboutWindow(bool* p_open)
 #ifdef __EMSCRIPTEN__
        ImGui::Text("define: __EMSCRIPTEN__");
        ImGui::Text("Emscripten: %d.%d.%d", __EMSCRIPTEN_major__, __EMSCRIPTEN_minor__, __EMSCRIPTEN_tiny__);
+#endif
+#ifdef IMGUI_HAS_VIEWPORT
+        ImGui::Text("define: IMGUI_HAS_VIEWPORT");
+#endif
+#ifdef IMGUI_HAS_DOCK
+        ImGui::Text("define: IMGUI_HAS_DOCK");
 #endif
        ImGui::Separator();
        ImGui::Text("io.BackendPlatformName: %s", io.BackendPlatformName ? io.BackendPlatformName : "NULL");
@@ -7764,7 +7845,19 @@ void ImGui::ShowAboutWindow(bool* p_open)
        if (io.ConfigFlags & ImGuiConfigFlags_NoMouse)                  ImGui::Text(" NoMouse");
        if (io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange)      ImGui::Text(" NoMouseCursorChange");
        if (io.ConfigFlags & ImGuiConfigFlags_NoKeyboard)               ImGui::Text(" NoKeyboard");
+        if (io.ConfigFlags & ImGuiConfigFlags_DockingEnable)            ImGui::Text(" DockingEnable");
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)          ImGui::Text(" ViewportsEnable");
+        if (io.ConfigFlags & ImGuiConfigFlags_DpiEnableScaleViewports)  ImGui::Text(" DpiEnableScaleViewports");
+        if (io.ConfigFlags & ImGuiConfigFlags_DpiEnableScaleFonts)      ImGui::Text(" DpiEnableScaleFonts");
        if (io.MouseDrawCursor)                                         ImGui::Text("io.MouseDrawCursor");
+        if (io.ConfigViewportsNoAutoMerge)                              ImGui::Text("io.ConfigViewportsNoAutoMerge");
+        if (io.ConfigViewportsNoTaskBarIcon)                            ImGui::Text("io.ConfigViewportsNoTaskBarIcon");
+        if (io.ConfigViewportsNoDecoration)                             ImGui::Text("io.ConfigViewportsNoDecoration");
+        if (io.ConfigViewportsNoDefaultParent)                          ImGui::Text("io.ConfigViewportsNoDefaultParent");
+        if (io.ConfigDockingNoSplit)                                    ImGui::Text("io.ConfigDockingNoSplit");
+        if (io.ConfigDockingWithShift)                                  ImGui::Text("io.ConfigDockingWithShift");
+        if (io.ConfigDockingAlwaysTabBar)                               ImGui::Text("io.ConfigDockingAlwaysTabBar");
+        if (io.ConfigDockingTransparentPayload)                         ImGui::Text("io.ConfigDockingTransparentPayload");
        if (io.ConfigMacOSXBehaviors)                                   ImGui::Text("io.ConfigMacOSXBehaviors");
        if (io.ConfigNavMoveSetMousePos)                                ImGui::Text("io.ConfigNavMoveSetMousePos");
        if (io.ConfigNavCaptureKeyboard)                                ImGui::Text("io.ConfigNavCaptureKeyboard");
@@ -7776,7 +7869,10 @@ void ImGui::ShowAboutWindow(bool* p_open)
        if (io.BackendFlags & ImGuiBackendFlags_HasGamepad)             ImGui::Text(" HasGamepad");
        if (io.BackendFlags & ImGuiBackendFlags_HasMouseCursors)        ImGui::Text(" HasMouseCursors");
        if (io.BackendFlags & ImGuiBackendFlags_HasSetMousePos)         ImGui::Text(" HasSetMousePos");
+        if (io.BackendFlags & ImGuiBackendFlags_PlatformHasViewports)   ImGui::Text(" PlatformHasViewports");
+        if (io.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)ImGui::Text(" HasMouseHoveredViewport");
        if (io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset)   ImGui::Text(" RendererHasVtxOffset");
+        if (io.BackendFlags & ImGuiBackendFlags_RendererHasViewports)   ImGui::Text(" RendererHasViewports");
        ImGui::Separator();
        ImGui::Text("io.Fonts: %d fonts, Flags: 0x%08X, TexSize: %d,%d", io.Fonts->Fonts.Size, io.Fonts->Flags, io.Fonts->TexWidth, io.Fonts->TexHeight);
        ImGui::Text("io.DisplaySize: %.2f,%.2f", io.DisplaySize.x, io.DisplaySize.y);
@@ -7952,6 +8048,9 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
            ImGui::SliderFloat2("SeparatorTextPadding", (float*)&style.SeparatorTextPadding, 0.0f, 40.0f, "%.0f");
            ImGui::SliderFloat("LogSliderDeadzone", &style.LogSliderDeadzone, 0.0f, 12.0f, "%.0f");

+            ImGui::SeparatorText("Docking");
+            ImGui::SliderFloat("DockingSplitterSize", &style.DockingSeparatorSize, 0.0f, 12.0f, "%.0f");
+
            ImGui::SeparatorText("Tooltips");
            for (int n = 0; n < 2; n++)
                if (ImGui::TreeNodeEx(n == 0 ? "HoverFlagsForTooltipMouse" : "HoverFlagsForTooltipNav"))
@@ -9198,6 +9297,8 @@ static void ShowExampleAppConstrainedResize(bool* p_open)
        else
        {
            ImGui::Text("(Hold SHIFT to display a dummy viewport)");
+            if (ImGui::IsWindowDocked())
+                ImGui::Text("Warning: Sizing Constraints won't work if the window is docked!");
            if (ImGui::Button("Set 200x200")) { ImGui::SetWindowSize(ImVec2(200, 200)); } ImGui::SameLine();
            if (ImGui::Button("Set 500x500")) { ImGui::SetWindowSize(ImVec2(500, 500)); } ImGui::SameLine();
            if (ImGui::Button("Set 800x200")) { ImGui::SetWindowSize(ImVec2(800, 200)); }
@@ -9224,7 +9325,7 @@ static void ShowExampleAppSimpleOverlay(bool* p_open)
 {
    static int location = 0;
    ImGuiIO& io = ImGui::GetIO();
-    ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing | ImGuiWindowFlags_NoNav;
+    ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoDocking | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing | ImGuiWindowFlags_NoNav;
    if (location >= 0)
    {
        const float PAD = 10.0f;
@@ -9237,6 +9338,7 @@ static void ShowExampleAppSimpleOverlay(bool* p_open)
        window_pos_pivot.x = (location & 1) ? 1.0f : 0.0f;
        window_pos_pivot.y = (location & 2) ? 1.0f : 0.0f;
        ImGui::SetNextWindowPos(window_pos, ImGuiCond_Always, window_pos_pivot);
+        ImGui::SetNextWindowViewport(viewport->ID);
        window_flags |= ImGuiWindowFlags_NoMove;
    }
    else if (location == -2)
@@ -9656,6 +9758,134 @@ static void ShowExampleAppCustomRendering(bool* p_open)
    ImGui::End();
 }

+//-----------------------------------------------------------------------------
+// [SECTION] Example App: Docking, DockSpace / ShowExampleAppDockSpace()
+//-----------------------------------------------------------------------------
+
+// Demonstrate using DockSpace() to create an explicit docking node within an existing window.
+// Note: You can use most Docking facilities without calling any API. You DO NOT need to call DockSpace() to use Docking!
+// - Drag from window title bar or their tab to dock/undock. Hold SHIFT to disable docking.
+// - Drag from window menu button (upper-left button) to undock an entire node (all windows).
+// - When io.ConfigDockingWithShift == true, you instead need to hold SHIFT to enable docking.
+// About dockspaces:
+// - Use DockSpace() to create an explicit dock node _within_ an existing window.
+// - Use DockSpaceOverViewport() to create an explicit dock node covering the screen or a specific viewport.
+//   This is often used with ImGuiDockNodeFlags_PassthruCentralNode.
+// - Important: Dockspaces need to be submitted _before_ any window they can host. Submit it early in your frame! (*)
+// - Important: Dockspaces need to be kept alive if hidden, otherwise windows docked into it will be undocked.
+//   e.g. if you have multiple tabs with a dockspace inside each tab: submit the non-visible dockspaces with ImGuiDockNodeFlags_KeepAliveOnly.
+// (*) because of this constraint, the implicit \"Debug\" window can not be docked into an explicit DockSpace() node,
+// because that window is submitted as part of the part of the NewFrame() call. An easy workaround is that you can create
+// your own implicit "Debug##2" window after calling DockSpace() and leave it in the window stack for anyone to use.
+void ShowExampleAppDockSpace(bool* p_open)
+{
+    // READ THIS !!!
+    // TL;DR; this demo is more complicated than what most users you would normally use.
+    // If we remove all options we are showcasing, this demo would become:
+    //     void ShowExampleAppDockSpace()
+    //     {
+    //         ImGui::DockSpaceOverViewport(0, ImGui::GetMainViewport());
+    //     }
+    // In most cases you should be able to just call DockSpaceOverViewport() and ignore all the code below!
+    // In this specific demo, we are not using DockSpaceOverViewport() because:
+    // - (1) we allow the host window to be floating/moveable instead of filling the viewport (when opt_fullscreen == false)
+    // - (2) we allow the host window to have padding (when opt_padding == true)
+    // - (3) we expose many flags and need a way to have them visible.
+    // - (4) we have a local menu bar in the host window (vs. you could use BeginMainMenuBar() + DockSpaceOverViewport()
+    //      in your code, but we don't here because we allow the window to be floating)
+
+    static bool opt_fullscreen = true;
+    static bool opt_padding = false;
+    static ImGuiDockNodeFlags dockspace_flags = ImGuiDockNodeFlags_None;
+
+    // We are using the ImGuiWindowFlags_NoDocking flag to make the parent window not dockable into,
+    // because it would be confusing to have two docking targets within each others.
+    ImGuiWindowFlags window_flags = ImGuiWindowFlags_MenuBar | ImGuiWindowFlags_NoDocking;
+    if (opt_fullscreen)
+    {
+        const ImGuiViewport* viewport = ImGui::GetMainViewport();
+        ImGui::SetNextWindowPos(viewport->WorkPos);
+        ImGui::SetNextWindowSize(viewport->WorkSize);
+        ImGui::SetNextWindowViewport(viewport->ID);
+        ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
+        ImGui::PushStyleVar(ImGuiStyleVar_WindowBorderSize, 0.0f);
+        window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove;
+        window_flags |= ImGuiWindowFlags_NoBringToFrontOnFocus | ImGuiWindowFlags_NoNavFocus;
+    }
+    else
+    {
+        dockspace_flags &= ~ImGuiDockNodeFlags_PassthruCentralNode;
+    }
+
+    // When using ImGuiDockNodeFlags_PassthruCentralNode, DockSpace() will render our background
+    // and handle the pass-thru hole, so we ask Begin() to not render a background.
+    if (dockspace_flags & ImGuiDockNodeFlags_PassthruCentralNode)
+        window_flags |= ImGuiWindowFlags_NoBackground;
+
+    // Important: note that we proceed even if Begin() returns false (aka window is collapsed).
+    // This is because we want to keep our DockSpace() active. If a DockSpace() is inactive,
+    // all active windows docked into it will lose their parent and become undocked.
+    // We cannot preserve the docking relationship between an active window and an inactive docking, otherwise
+    // any change of dockspace/settings would lead to windows being stuck in limbo and never being visible.
+    if (!opt_padding)
+        ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0.0f, 0.0f));
+    ImGui::Begin("DockSpace Demo", p_open, window_flags);
+    if (!opt_padding)
+        ImGui::PopStyleVar();
+
+    if (opt_fullscreen)
+        ImGui::PopStyleVar(2);
+
+    // Submit the DockSpace
+    ImGuiIO& io = ImGui::GetIO();
+    if (io.ConfigFlags & ImGuiConfigFlags_DockingEnable)
+    {
+        ImGuiID dockspace_id = ImGui::GetID("MyDockSpace");
+        ImGui::DockSpace(dockspace_id, ImVec2(0.0f, 0.0f), dockspace_flags);
+    }
+    else
+    {
+        ShowDockingDisabledMessage();
+    }
+
+    if (ImGui::BeginMenuBar())
+    {
+        if (ImGui::BeginMenu("Options"))
+        {
+            // Disabling fullscreen would allow the window to be moved to the front of other windows,
+            // which we can't undo at the moment without finer window depth/z control.
+            ImGui::MenuItem("Fullscreen", NULL, &opt_fullscreen);
+            ImGui::MenuItem("Padding", NULL, &opt_padding);
+            ImGui::Separator();
+
+            if (ImGui::MenuItem("Flag: NoDockingOverCentralNode", "", (dockspace_flags & ImGuiDockNodeFlags_NoDockingOverCentralNode) != 0)) { dockspace_flags ^= ImGuiDockNodeFlags_NoDockingOverCentralNode; }
+            if (ImGui::MenuItem("Flag: NoDockingSplit",         "", (dockspace_flags & ImGuiDockNodeFlags_NoDockingSplit) != 0))             { dockspace_flags ^= ImGuiDockNodeFlags_NoDockingSplit; }
+            if (ImGui::MenuItem("Flag: NoUndocking",            "", (dockspace_flags & ImGuiDockNodeFlags_NoUndocking) != 0))                { dockspace_flags ^= ImGuiDockNodeFlags_NoUndocking; }
+            if (ImGui::MenuItem("Flag: NoResize",               "", (dockspace_flags & ImGuiDockNodeFlags_NoResize) != 0))                   { dockspace_flags ^= ImGuiDockNodeFlags_NoResize; }
+            if (ImGui::MenuItem("Flag: AutoHideTabBar",         "", (dockspace_flags & ImGuiDockNodeFlags_AutoHideTabBar) != 0))             { dockspace_flags ^= ImGuiDockNodeFlags_AutoHideTabBar; }
+            if (ImGui::MenuItem("Flag: PassthruCentralNode",    "", (dockspace_flags & ImGuiDockNodeFlags_PassthruCentralNode) != 0, opt_fullscreen)) { dockspace_flags ^= ImGuiDockNodeFlags_PassthruCentralNode; }
+            ImGui::Separator();
+
+            if (ImGui::MenuItem("Close", NULL, false, p_open != NULL))
+                *p_open = false;
+            ImGui::EndMenu();
+        }
+        HelpMarker(
+            "When docking is enabled, you can ALWAYS dock MOST window into another! Try it now!" "\n"
+            "- Drag from window title bar or their tab to dock/undock." "\n"
+            "- Drag from window menu button (upper-left button) to undock an entire node (all windows)." "\n"
+            "- Hold SHIFT to disable docking (if io.ConfigDockingWithShift == false, default)" "\n"
+            "- Hold SHIFT to enable docking (if io.ConfigDockingWithShift == true)" "\n"
+            "This demo app has nothing to do with enabling docking!" "\n\n"
+            "This demo app only demonstrate the use of ImGui::DockSpace() which allows you to manually create a docking node _within_ another window." "\n\n"
+            "Read comments in ShowExampleAppDockSpace() for more details.");
+
+        ImGui::EndMenuBar();
+    }
+
+    ImGui::End();
+}
+
 //-----------------------------------------------------------------------------
 // [SECTION] Example App: Documents Handling / ShowExampleAppDocuments()
 //-----------------------------------------------------------------------------
@@ -9781,11 +10011,25 @@ void ShowExampleAppDocuments(bool* p_open)
    static ExampleAppDocuments app;

    // Options
+    enum Target
+    {
+        Target_None,
+        Target_Tab,                 // Create documents as local tab into a local tab bar
+        Target_DockSpaceAndWindow   // Create documents as regular windows, and create an embedded dockspace
+    };
+    static Target opt_target = Target_Tab;
    static bool opt_reorderable = true;
    static ImGuiTabBarFlags opt_fitting_flags = ImGuiTabBarFlags_FittingPolicyDefault_;

+    // When (opt_target == Target_DockSpaceAndWindow) there is the possibily that one of our child Document window (e.g. "Eggplant")
+    // that we emit gets docked into the same spot as the parent window ("Example: Documents").
+    // This would create a problematic feedback loop because selecting the "Eggplant" tab would make the "Example: Documents" tab
+    // not visible, which in turn would stop submitting the "Eggplant" window.
+    // We avoid this problem by submitting our documents window even if our parent window is not currently visible.
+    // Another solution may be to make the "Example: Documents" window use the ImGuiWindowFlags_NoDocking.
+
    bool window_contents_visible = ImGui::Begin("Example: Documents", p_open, ImGuiWindowFlags_MenuBar);
-    if (!window_contents_visible)
+    if (!window_contents_visible && opt_target != Target_DockSpaceAndWindow)
    {
        ImGui::End();
        return;
@@ -9829,6 +10073,12 @@ void ShowExampleAppDocuments(bool* p_open)
                doc.DoForceClose();
        ImGui::PopID();
    }
+    ImGui::PushItemWidth(ImGui::GetFontSize() * 12);
+    ImGui::Combo("Output", (int*)&opt_target, "None\0TabBar+Tabs\0DockSpace+Window\0");
+    ImGui::PopItemWidth();
+    bool redock_all = false;
+    if (opt_target == Target_Tab)                { ImGui::SameLine(); ImGui::Checkbox("Reorderable Tabs", &opt_reorderable); }
+    if (opt_target == Target_DockSpaceAndWindow) { ImGui::SameLine(); redock_all = ImGui::Button("Redock all"); }

    ImGui::Separator();

@@ -9842,7 +10092,8 @@ void ShowExampleAppDocuments(bool* p_open)
    //   hole for one-frame, both in the tab-bar and in tab-contents when closing a tab/window.
    //   The rarely used SetTabItemClosed() function is a way to notify of programmatic closure to avoid the one-frame hole.

-    // Submit Tab Bar and Tabs
+    // Tabs
+    if (opt_target == Target_Tab)
    {
        ImGuiTabBarFlags tab_bar_flags = (opt_fitting_flags) | (opt_reorderable ? ImGuiTabBarFlags_Reorderable : 0);
        tab_bar_flags |= ImGuiTabBarFlags_DrawSelectedOverline;
@@ -9885,6 +10136,53 @@ void ShowExampleAppDocuments(bool* p_open)
            ImGui::EndTabBar();
        }
    }
+    else if (opt_target == Target_DockSpaceAndWindow)
+    {
+        if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_DockingEnable)
+        {
+            app.NotifyOfDocumentsClosedElsewhere();
+
+            // Create a DockSpace node where any window can be docked
+            ImGuiID dockspace_id = ImGui::GetID("MyDockSpace");
+            ImGui::DockSpace(dockspace_id);
+
+            // Create Windows
+            for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+            {
+                MyDocument* doc = &app.Documents[doc_n];
+                if (!doc->Open)
+                    continue;
+
+                ImGui::SetNextWindowDockID(dockspace_id, redock_all ? ImGuiCond_Always : ImGuiCond_FirstUseEver);
+                ImGuiWindowFlags window_flags = (doc->Dirty ? ImGuiWindowFlags_UnsavedDocument : 0);
+                bool visible = ImGui::Begin(doc->Name, &doc->Open, window_flags);
+
+                // Cancel attempt to close when unsaved add to save queue so we can display a popup.
+                if (!doc->Open && doc->Dirty)
+                {
+                    doc->Open = true;
+                    app.CloseQueue.push_back(doc);
+                }
+
+                app.DisplayDocContextMenu(doc);
+                if (visible)
+                    app.DisplayDocContents(doc);
+
+                ImGui::End();
+            }
+        }
+        else
+        {
+            ShowDockingDisabledMessage();
+        }
+    }
+
+    // Early out other contents
+    if (!window_contents_visible)
+    {
+        ImGui::End();
+        return;
+    }

    // Display renaming UI
    if (app.RenamingDoc != NULL)
@@ -219,6 +219,8 @@ void ImGui::StyleColorsDark(ImGuiStyle* dst)
    colors[ImGuiCol_TabDimmed]              = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
    colors[ImGuiCol_TabDimmedSelected]      = ImLerp(colors[ImGuiCol_TabSelected],  colors[ImGuiCol_TitleBg], 0.40f);
    colors[ImGuiCol_TabDimmedSelectedOverline] = ImVec4(0.50f, 0.50f, 0.50f, 0.00f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_HeaderActive] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
    colors[ImGuiCol_PlotLines]              = ImVec4(0.61f, 0.61f, 0.61f, 1.00f);
    colors[ImGuiCol_PlotLinesHovered]       = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
    colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -282,6 +284,8 @@ void ImGui::StyleColorsClassic(ImGuiStyle* dst)
    colors[ImGuiCol_TabDimmed]              = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
    colors[ImGuiCol_TabDimmedSelected]      = ImLerp(colors[ImGuiCol_TabSelected],  colors[ImGuiCol_TitleBg], 0.40f);
    colors[ImGuiCol_TabDimmedSelectedOverline] = ImVec4(0.53f, 0.53f, 0.87f, 0.00f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_Header] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
    colors[ImGuiCol_PlotLines]              = ImVec4(1.00f, 1.00f, 1.00f, 1.00f);
    colors[ImGuiCol_PlotLinesHovered]       = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
    colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -346,6 +350,8 @@ void ImGui::StyleColorsLight(ImGuiStyle* dst)
    colors[ImGuiCol_TabDimmed]              = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
    colors[ImGuiCol_TabDimmedSelected]      = ImLerp(colors[ImGuiCol_TabSelected],  colors[ImGuiCol_TitleBg], 0.40f);
    colors[ImGuiCol_TabDimmedSelectedOverline] = ImVec4(0.26f, 0.59f, 1.00f, 0.00f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_Header] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
    colors[ImGuiCol_PlotLines]              = ImVec4(0.39f, 0.39f, 0.39f, 1.00f);
    colors[ImGuiCol_PlotLinesHovered]       = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
    colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -4247,6 +4253,7 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, const ImVec2& pos, Im
 // - RenderArrow()
 // - RenderBullet()
 // - RenderCheckMark()
+// - RenderArrowDockMenu()
 // - RenderArrowPointingAt()
 // - RenderRectFilledRangeH()
 // - RenderRectFilledWithHole()
@@ -4321,6 +4328,14 @@ void ImGui::RenderArrowPointingAt(ImDrawList* draw_list, ImVec2 pos, ImVec2 half
    }
 }

+// This is less wide than RenderArrow() and we use in dock nodes instead of the regular RenderArrow() to denote a change of functionality,
+// and because the saved space means that the left-most tab label can stay at exactly the same position as the label of a loose window.
+void ImGui::RenderArrowDockMenu(ImDrawList* draw_list, ImVec2 p_min, float sz, ImU32 col)
+{
+    draw_list->AddRectFilled(p_min + ImVec2(sz * 0.20f, sz * 0.15f), p_min + ImVec2(sz * 0.80f, sz * 0.30f), col);
+    RenderArrowPointingAt(draw_list, p_min + ImVec2(sz * 0.50f, sz * 0.85f), ImVec2(sz * 0.30f, sz * 0.40f), ImGuiDir_Down, col);
+}
+
 static inline float ImAcos01(float x)
 {
    if (x <= 0.0f) return IM_PI * 0.5f;
@@ -4406,6 +4421,17 @@ void ImGui::RenderRectFilledWithHole(ImDrawList* draw_list, const ImRect& outer,
    if (fill_R && fill_D) draw_list->AddRectFilled(ImVec2(inner.Max.x, inner.Max.y), ImVec2(outer.Max.x, outer.Max.y), col, rounding, ImDrawFlags_RoundCornersBottomRight);
 }

+ImDrawFlags ImGui::CalcRoundingFlagsForRectInRect(const ImRect& r_in, const ImRect& r_outer, float threshold)
+{
+    bool round_l = r_in.Min.x <= r_outer.Min.x + threshold;
+    bool round_r = r_in.Max.x >= r_outer.Max.x - threshold;
+    bool round_t = r_in.Min.y <= r_outer.Min.y + threshold;
+    bool round_b = r_in.Max.y >= r_outer.Max.y - threshold;
+    return ImDrawFlags_RoundCornersNone
+        | ((round_t && round_l) ? ImDrawFlags_RoundCornersTopLeft : 0) | ((round_t && round_r) ? ImDrawFlags_RoundCornersTopRight : 0)
+        | ((round_b && round_l) ? ImDrawFlags_RoundCornersBottomLeft : 0) | ((round_b && round_r) ? ImDrawFlags_RoundCornersBottomRight : 0);
+}
+
 // Helper for ColorPicker4()
 // NB: This is rather brittle and will show artifact when rounding this enabled if rounded corners overlap multiple cells. Caller currently responsible for avoiding that.
 // Spent a non reasonable amount of time trying to getting this right for ColorButton with rounding+anti-aliasing+ImGuiColorEditFlags_HalfAlphaPreview flag + various grid sizes and offsets, and eventually gave up... probably more reasonable to disable rounding altogether.
@@ -131,6 +131,10 @@ struct ImGuiContext;                // Main Dear ImGui context
 struct ImGuiContextHook;            // Hook for extensions like ImGuiTestEngine
 struct ImGuiDataVarInfo;            // Variable information (e.g. to access style variables from an enum)
 struct ImGuiDataTypeInfo;           // Type information associated to a ImGuiDataType enum
+struct ImGuiDockContext;            // Docking system context
+struct ImGuiDockRequest;            // Docking system dock/undock queued request
+struct ImGuiDockNode;               // Docking system node (hold a list of Windows OR two child dock nodes)
+struct ImGuiDockNodeSettings;       // Storage for a dock node in .ini file (we preserve those even if the associated dock node isn't active during the session)
 struct ImGuiErrorRecoveryState;     // Storage of stack sizes for error handling and recovery
 struct ImGuiGroupData;              // Stacked storage data for BeginGroup()/EndGroup()
 struct ImGuiInputTextState;         // Internal state of the currently focused/edited text input box
@@ -162,12 +166,14 @@ struct ImGuiTreeNodeStackData;      // Temporary storage for TreeNode().
 struct ImGuiTypingSelectState;      // Storage for GetTypingSelectRequest()
 struct ImGuiTypingSelectRequest;    // Storage for GetTypingSelectRequest() (aimed to be public)
 struct ImGuiWindow;                 // Storage for one window
+struct ImGuiWindowDockStyle;        // Storage for window-style data which needs to be stored for docking purpose
 struct ImGuiWindowTempData;         // Temporary storage for one window (that's the data which in theory we could ditch at the end of the frame, in practice we currently keep it for each window)
 struct ImGuiWindowSettings;         // Storage for a window .ini settings (we keep one of those even if the actual window wasn't instanced during this session)

 // Enumerations
 // Use your programming IDE "Go to definition" facility on the names of the center columns to find the actual flags/enum lists.
 enum ImGuiLocKey : int;                 // -> enum ImGuiLocKey              // Enum: a localization entry for translation.
+typedef int ImGuiDataAuthority;         // -> enum ImGuiDataAuthority_      // Enum: for storing the source authority (dock node vs window) of a field
 typedef int ImGuiLayoutType;            // -> enum ImGuiLayoutType_         // Enum: Horizontal or vertical

 // Flags
@@ -201,6 +207,9 @@ extern IMGUI_API ImGuiContext* GImGui;  // Current implicit context pointer
 // [SECTION] Macros
 //-----------------------------------------------------------------------------

+// Internal Drag and Drop payload types. String starting with '_' are reserved for Dear ImGui.
+#define IMGUI_PAYLOAD_TYPE_WINDOW       "_IMWINDOW"     // Payload == ImGuiWindow*
+
 // Debug Printing Into TTY
 // (since IMGUI_VERSION_NUM >= 18729: IMGUI_DEBUG_LOG was reworked into IMGUI_DEBUG_PRINTF (and removed framecount from it). If you were using a #define IMGUI_DEBUG_LOG please rename)
 #ifndef IMGUI_DEBUG_PRINTF
@@ -226,6 +235,8 @@ extern IMGUI_API ImGuiContext* GImGui;  // Current implicit context pointer
 #define IMGUI_DEBUG_LOG_CLIPPER(...)    do { if (g.DebugLogFlags & ImGuiDebugLogFlags_EventClipper)     IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)
 #define IMGUI_DEBUG_LOG_IO(...)         do { if (g.DebugLogFlags & ImGuiDebugLogFlags_EventIO)          IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)
 #define IMGUI_DEBUG_LOG_INPUTROUTING(...) do{if (g.DebugLogFlags & ImGuiDebugLogFlags_EventInputRouting)IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)
+#define IMGUI_DEBUG_LOG_DOCKING(...)    do { if (g.DebugLogFlags & ImGuiDebugLogFlags_EventDocking)     IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)
+#define IMGUI_DEBUG_LOG_VIEWPORT(...)   do { if (g.DebugLogFlags & ImGuiDebugLogFlags_EventViewport)    IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)

 // Static Asserts
 #define IM_STATIC_ASSERT(_COND)         static_assert(_COND, "")
@@ -887,7 +898,7 @@ enum ImGuiItemStatusFlags_
 enum ImGuiHoveredFlagsPrivate_
 {
    ImGuiHoveredFlags_DelayMask_                    = ImGuiHoveredFlags_DelayNone | ImGuiHoveredFlags_DelayShort | ImGuiHoveredFlags_DelayNormal | ImGuiHoveredFlags_NoSharedDelay,
-    ImGuiHoveredFlags_AllowedMaskForIsWindowHovered = ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_AnyWindow | ImGuiHoveredFlags_NoPopupHierarchy | ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem | ImGuiHoveredFlags_ForTooltip | ImGuiHoveredFlags_Stationary,
+    ImGuiHoveredFlags_AllowedMaskForIsWindowHovered = ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_AnyWindow | ImGuiHoveredFlags_NoPopupHierarchy | ImGuiHoveredFlags_DockHierarchy | ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem | ImGuiHoveredFlags_ForTooltip | ImGuiHoveredFlags_Stationary,
    ImGuiHoveredFlags_AllowedMaskForIsItemHovered   = ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem | ImGuiHoveredFlags_AllowWhenOverlapped | ImGuiHoveredFlags_AllowWhenDisabled | ImGuiHoveredFlags_NoNavOverride | ImGuiHoveredFlags_ForTooltip | ImGuiHoveredFlags_Stationary | ImGuiHoveredFlags_DelayMask_,
 };

@@ -1182,6 +1193,9 @@ enum ImGuiNextWindowDataFlags_
    ImGuiNextWindowDataFlags_HasScroll          = 1 << 7,
    ImGuiNextWindowDataFlags_HasChildFlags      = 1 << 8,
    ImGuiNextWindowDataFlags_HasRefreshPolicy   = 1 << 9,
+    ImGuiNextWindowDataFlags_HasViewport        = 1 << 10,
+    ImGuiNextWindowDataFlags_HasDock            = 1 << 11,
+    ImGuiNextWindowDataFlags_HasWindowClass     = 1 << 12,
 };

 // Storage for SetNexWindow** functions
@@ -1191,17 +1205,22 @@ struct ImGuiNextWindowData
    ImGuiCond                   PosCond;
    ImGuiCond                   SizeCond;
    ImGuiCond                   CollapsedCond;
+    ImGuiCond                   DockCond;
    ImVec2                      PosVal;
    ImVec2                      PosPivotVal;
    ImVec2                      SizeVal;
    ImVec2                      ContentSizeVal;
    ImVec2                      ScrollVal;
    ImGuiChildFlags             ChildFlags;
+    bool                        PosUndock;
    bool                        CollapsedVal;
    ImRect                      SizeConstraintRect;
    ImGuiSizeCallback           SizeCallback;
    void*                       SizeCallbackUserData;
    float                       BgAlphaVal;             // Override background alpha
+    ImGuiID                     ViewportId;
+    ImGuiID                     DockId;
+    ImGuiWindowClass            WindowClass;
    ImVec2                      MenuBarOffsetMinVal;    // (Always on) This is not exposed publicly, so we don't clear it and it doesn't have a corresponding flag (could we? for consistency?)
    ImGuiWindowRefreshFlags     RefreshFlagsVal;

@@ -1370,6 +1389,7 @@ enum ImGuiInputEventType
    ImGuiInputEventType_MousePos,
    ImGuiInputEventType_MouseWheel,
    ImGuiInputEventType_MouseButton,
+    ImGuiInputEventType_MouseViewport,
    ImGuiInputEventType_Key,
    ImGuiInputEventType_Text,
    ImGuiInputEventType_Focus,
@@ -1390,6 +1410,7 @@ enum ImGuiInputSource
 struct ImGuiInputEventMousePos      { float PosX, PosY; ImGuiMouseSource MouseSource; };
 struct ImGuiInputEventMouseWheel    { float WheelX, WheelY; ImGuiMouseSource MouseSource; };
 struct ImGuiInputEventMouseButton   { int Button; bool Down; ImGuiMouseSource MouseSource; };
+struct ImGuiInputEventMouseViewport { ImGuiID HoveredViewportID; };
 struct ImGuiInputEventKey           { ImGuiKey Key; bool Down; float AnalogValue; };
 struct ImGuiInputEventText          { unsigned int Char; };
 struct ImGuiInputEventAppFocused    { bool Focused; };
@@ -1404,6 +1425,7 @@ struct ImGuiInputEvent
        ImGuiInputEventMousePos     MousePos;       // if Type == ImGuiInputEventType_MousePos
        ImGuiInputEventMouseWheel   MouseWheel;     // if Type == ImGuiInputEventType_MouseWheel
        ImGuiInputEventMouseButton  MouseButton;    // if Type == ImGuiInputEventType_MouseButton
+        ImGuiInputEventMouseViewport MouseViewport; // if Type == ImGuiInputEventType_MouseViewport
        ImGuiInputEventKey          Key;            // if Type == ImGuiInputEventType_Key
        ImGuiInputEventText         Text;           // if Type == ImGuiInputEventType_Text
        ImGuiInputEventAppFocused   AppFocused;     // if Type == ImGuiInputEventType_Focus
@@ -1797,8 +1819,153 @@ struct IMGUI_API ImGuiMultiSelectState
 // [SECTION] Docking support
 //-----------------------------------------------------------------------------

+#define DOCKING_HOST_DRAW_CHANNEL_BG 0  // Dock host: background fill
+#define DOCKING_HOST_DRAW_CHANNEL_FG 1  // Dock host: decorations and contents
+
 #ifdef IMGUI_HAS_DOCK
-// <this is filled in 'docking' branch>
+
+// Extend ImGuiDockNodeFlags_
+enum ImGuiDockNodeFlagsPrivate_
+{
+    // [Internal]
+    ImGuiDockNodeFlags_DockSpace                = 1 << 10,  // Saved // A dockspace is a node that occupy space within an existing user window. Otherwise the node is floating and create its own window.
+    ImGuiDockNodeFlags_CentralNode              = 1 << 11,  // Saved // The central node has 2 main properties: stay visible when empty, only use "remaining" spaces from its neighbor.
+    ImGuiDockNodeFlags_NoTabBar                 = 1 << 12,  // Saved // Tab bar is completely unavailable. No triangle in the corner to enable it back.
+    ImGuiDockNodeFlags_HiddenTabBar             = 1 << 13,  // Saved // Tab bar is hidden, with a triangle in the corner to show it again (NB: actual tab-bar instance may be destroyed as this is only used for single-window tab bar)
+    ImGuiDockNodeFlags_NoWindowMenuButton       = 1 << 14,  // Saved // Disable window/docking menu (that one that appears instead of the collapse button)
+    ImGuiDockNodeFlags_NoCloseButton            = 1 << 15,  // Saved // Disable close button
+    ImGuiDockNodeFlags_NoResizeX                = 1 << 16,  //       //
+    ImGuiDockNodeFlags_NoResizeY                = 1 << 17,  //       //
+    ImGuiDockNodeFlags_DockedWindowsInFocusRoute= 1 << 18,  //       // Any docked window will be automatically be focus-route chained (window->ParentWindowForFocusRoute set to this) so Shortcut() in this window can run when any docked window is focused.
+    // Disable docking/undocking actions in this dockspace or individual node (existing docked nodes will be preserved)
+    // Those are not exposed in public because the desirable sharing/inheriting/copy-flag-on-split behaviors are quite difficult to design and understand.
+    // The two public flags ImGuiDockNodeFlags_NoDockingOverCentralNode/ImGuiDockNodeFlags_NoDockingSplit don't have those issues.
+    ImGuiDockNodeFlags_NoDockingSplitOther      = 1 << 19,  //       // Disable this node from splitting other windows/nodes.
+    ImGuiDockNodeFlags_NoDockingOverMe          = 1 << 20,  //       // Disable other windows/nodes from being docked over this node.
+    ImGuiDockNodeFlags_NoDockingOverOther       = 1 << 21,  //       // Disable this node from being docked over another window or non-empty node.
+    ImGuiDockNodeFlags_NoDockingOverEmpty       = 1 << 22,  //       // Disable this node from being docked over an empty node (e.g. DockSpace with no other windows)
+    ImGuiDockNodeFlags_NoDocking                = ImGuiDockNodeFlags_NoDockingOverMe | ImGuiDockNodeFlags_NoDockingOverOther | ImGuiDockNodeFlags_NoDockingOverEmpty | ImGuiDockNodeFlags_NoDockingSplit | ImGuiDockNodeFlags_NoDockingSplitOther,
+    // Masks
+    ImGuiDockNodeFlags_SharedFlagsInheritMask_  = ~0,
+    ImGuiDockNodeFlags_NoResizeFlagsMask_       = (int)ImGuiDockNodeFlags_NoResize | ImGuiDockNodeFlags_NoResizeX | ImGuiDockNodeFlags_NoResizeY,
+
+    // When splitting, those local flags are moved to the inheriting child, never duplicated
+    ImGuiDockNodeFlags_LocalFlagsTransferMask_  = (int)ImGuiDockNodeFlags_NoDockingSplit | ImGuiDockNodeFlags_NoResizeFlagsMask_ | (int)ImGuiDockNodeFlags_AutoHideTabBar | ImGuiDockNodeFlags_CentralNode | ImGuiDockNodeFlags_NoTabBar | ImGuiDockNodeFlags_HiddenTabBar | ImGuiDockNodeFlags_NoWindowMenuButton | ImGuiDockNodeFlags_NoCloseButton,
+    ImGuiDockNodeFlags_SavedFlagsMask_          = ImGuiDockNodeFlags_NoResizeFlagsMask_ | ImGuiDockNodeFlags_DockSpace | ImGuiDockNodeFlags_CentralNode | ImGuiDockNodeFlags_NoTabBar | ImGuiDockNodeFlags_HiddenTabBar | ImGuiDockNodeFlags_NoWindowMenuButton | ImGuiDockNodeFlags_NoCloseButton,
+};
+
+// Store the source authority (dock node vs window) of a field
+enum ImGuiDataAuthority_
+{
+    ImGuiDataAuthority_Auto,
+    ImGuiDataAuthority_DockNode,
+    ImGuiDataAuthority_Window,
+};
+
+enum ImGuiDockNodeState
+{
+    ImGuiDockNodeState_Unknown,
+    ImGuiDockNodeState_HostWindowHiddenBecauseSingleWindow,
+    ImGuiDockNodeState_HostWindowHiddenBecauseWindowsAreResizing,
+    ImGuiDockNodeState_HostWindowVisible,
+};
+
+// sizeof() 156~192
+struct IMGUI_API ImGuiDockNode
+{
+    ImGuiID                 ID;
+    ImGuiDockNodeFlags      SharedFlags;                // (Write) Flags shared by all nodes of a same dockspace hierarchy (inherited from the root node)
+    ImGuiDockNodeFlags      LocalFlags;                 // (Write) Flags specific to this node
+    ImGuiDockNodeFlags      LocalFlagsInWindows;        // (Write) Flags specific to this node, applied from windows
+    ImGuiDockNodeFlags      MergedFlags;                // (Read)  Effective flags (== SharedFlags | LocalFlagsInNode | LocalFlagsInWindows)
+    ImGuiDockNodeState      State;
+    ImGuiDockNode*          ParentNode;
+    ImGuiDockNode*          ChildNodes[2];              // [Split node only] Child nodes (left/right or top/bottom). Consider switching to an array.
+    ImVector<ImGuiWindow*>  Windows;                    // Note: unordered list! Iterate TabBar->Tabs for user-order.
+    ImGuiTabBar*            TabBar;
+    ImVec2                  Pos;                        // Current position
+    ImVec2                  Size;                       // Current size
+    ImVec2                  SizeRef;                    // [Split node only] Last explicitly written-to size (overridden when using a splitter affecting the node), used to calculate Size.
+    ImGuiAxis               SplitAxis;                  // [Split node only] Split axis (X or Y)
+    ImGuiWindowClass        WindowClass;                // [Root node only]
+    ImU32                   LastBgColor;
+
+    ImGuiWindow*            HostWindow;
+    ImGuiWindow*            VisibleWindow;              // Generally point to window which is ID is == SelectedTabID, but when CTRL+Tabbing this can be a different window.
+    ImGuiDockNode*          CentralNode;                // [Root node only] Pointer to central node.
+    ImGuiDockNode*          OnlyNodeWithWindows;        // [Root node only] Set when there is a single visible node within the hierarchy.
+    int                     CountNodeWithWindows;       // [Root node only]
+    int                     LastFrameAlive;             // Last frame number the node was updated or kept alive explicitly with DockSpace() + ImGuiDockNodeFlags_KeepAliveOnly
+    int                     LastFrameActive;            // Last frame number the node was updated.
+    int                     LastFrameFocused;           // Last frame number the node was focused.
+    ImGuiID                 LastFocusedNodeId;          // [Root node only] Which of our child docking node (any ancestor in the hierarchy) was last focused.
+    ImGuiID                 SelectedTabId;              // [Leaf node only] Which of our tab/window is selected.
+    ImGuiID                 WantCloseTabId;             // [Leaf node only] Set when closing a specific tab/window.
+    ImGuiID                 RefViewportId;              // Reference viewport ID from visible window when HostWindow == NULL.
+    ImGuiDataAuthority      AuthorityForPos         :3;
+    ImGuiDataAuthority      AuthorityForSize        :3;
+    ImGuiDataAuthority      AuthorityForViewport    :3;
+    bool                    IsVisible               :1; // Set to false when the node is hidden (usually disabled as it has no active window)
+    bool                    IsFocused               :1;
+    bool                    IsBgDrawnThisFrame      :1;
+    bool                    HasCloseButton          :1; // Provide space for a close button (if any of the docked window has one). Note that button may be hidden on window without one.
+    bool                    HasWindowMenuButton     :1;
+    bool                    HasCentralNodeChild     :1;
+    bool                    WantCloseAll            :1; // Set when closing all tabs at once.
+    bool                    WantLockSizeOnce        :1;
+    bool                    WantMouseMove           :1; // After a node extraction we need to transition toward moving the newly created host window
+    bool                    WantHiddenTabBarUpdate  :1;
+    bool                    WantHiddenTabBarToggle  :1;
+
+    ImGuiDockNode(ImGuiID id);
+    ~ImGuiDockNode();
+    bool                    IsRootNode() const      { return ParentNode == NULL; }
+    bool                    IsDockSpace() const     { return (MergedFlags & ImGuiDockNodeFlags_DockSpace) != 0; }
+    bool                    IsFloatingNode() const  { return ParentNode == NULL && (MergedFlags & ImGuiDockNodeFlags_DockSpace) == 0; }
+    bool                    IsCentralNode() const   { return (MergedFlags & ImGuiDockNodeFlags_CentralNode) != 0; }
+    bool                    IsHiddenTabBar() const  { return (MergedFlags & ImGuiDockNodeFlags_HiddenTabBar) != 0; } // Hidden tab bar can be shown back by clicking the small triangle
+    bool                    IsNoTabBar() const      { return (MergedFlags & ImGuiDockNodeFlags_NoTabBar) != 0; }     // Never show a tab bar
+    bool                    IsSplitNode() const     { return ChildNodes[0] != NULL; }
+    bool                    IsLeafNode() const      { return ChildNodes[0] == NULL; }
+    bool                    IsEmpty() const         { return ChildNodes[0] == NULL && Windows.Size == 0; }
+    ImRect                  Rect() const            { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
+
+    void                    SetLocalFlags(ImGuiDockNodeFlags flags) { LocalFlags = flags; UpdateMergedFlags(); }
+    void                    UpdateMergedFlags()     { MergedFlags = SharedFlags | LocalFlags | LocalFlagsInWindows; }
+};
+
+// List of colors that are stored at the time of Begin() into Docked Windows.
+// We currently store the packed colors in a simple array window->DockStyle.Colors[].
+// A better solution may involve appending into a log of colors in ImGuiContext + store offsets into those arrays in ImGuiWindow,
+// but it would be more complex as we'd need to double-buffer both as e.g. drop target may refer to window from last frame.
+enum ImGuiWindowDockStyleCol
+{
+    ImGuiWindowDockStyleCol_Text,
+    ImGuiWindowDockStyleCol_TabHovered,
+    ImGuiWindowDockStyleCol_TabFocused,
+    ImGuiWindowDockStyleCol_TabSelected,
+    ImGuiWindowDockStyleCol_TabSelectedOverline,
+    ImGuiWindowDockStyleCol_TabDimmed,
+    ImGuiWindowDockStyleCol_TabDimmedSelected,
+    ImGuiWindowDockStyleCol_TabDimmedSelectedOverline,
+    ImGuiWindowDockStyleCol_COUNT
+};
+
+// We don't store style.Alpha: dock_node->LastBgColor embeds it and otherwise it would only affect the docking tab, which intuitively I would say we don't want to.
+struct ImGuiWindowDockStyle
+{
+    ImU32 Colors[ImGuiWindowDockStyleCol_COUNT];
+};
+
+struct ImGuiDockContext
+{
+    ImGuiStorage                    Nodes;          // Map ID -> ImGuiDockNode*: Active nodes
+    ImVector<ImGuiDockRequest>      Requests;
+    ImVector<ImGuiDockNodeSettings> NodesSettings;
+    bool                            WantFullRebuild;
+    ImGuiDockContext()              { memset(this, 0, sizeof(*this)); }
+};
+
 #endif // #ifdef IMGUI_HAS_DOCK

 //-----------------------------------------------------------------------------
@@ -1809,10 +1976,24 @@ struct IMGUI_API ImGuiMultiSelectState
 // Every instance of ImGuiViewport is in fact a ImGuiViewportP.
 struct ImGuiViewportP : public ImGuiViewport
 {
+    ImGuiWindow*        Window;                 // Set when the viewport is owned by a window (and ImGuiViewportFlags_CanHostOtherWindows is NOT set)
+    int                 Idx;
+    int                 LastFrameActive;        // Last frame number this viewport was activated by a window
+    int                 LastFocusedStampCount;  // Last stamp number from when a window hosted by this viewport was focused (by comparing this value between two viewport we have an implicit viewport z-order we use as fallback)
+    ImGuiID             LastNameHash;
+    ImVec2              LastPos;
+    ImVec2              LastSize;
+    float               Alpha;                  // Window opacity (when dragging dockable windows/viewports we make them transparent)
+    float               LastAlpha;
+    bool                LastFocusedHadNavWindow;// Instead of maintaining a LastFocusedWindow (which may harder to correctly maintain), we merely store weither NavWindow != NULL last time the viewport was focused.
+    short               PlatformMonitor;
    int                 BgFgDrawListsLastFrame[2]; // Last frame number the background (0) and foreground (1) draw lists were used
    ImDrawList*         BgFgDrawLists[2];       // Convenience background (0) and foreground (1) draw lists. We use them to draw software mouser cursor when io.MouseDrawCursor is set and to draw most debug overlays.
    ImDrawData          DrawDataP;
    ImDrawDataBuilder   DrawDataBuilder;        // Temporary data while building final ImDrawData
+    ImVec2              LastPlatformPos;
+    ImVec2              LastPlatformSize;
+    ImVec2              LastRendererSize;

    // Per-viewport work area
    // - Insets are >= 0.0f values, distance from viewport corners to work area.
@@ -1823,8 +2004,9 @@ struct ImGuiViewportP : public ImGuiViewport
    ImVec2              BuildWorkInsetMin;      // Work Area inset accumulator for current frame, to become next frame's WorkInset
    ImVec2              BuildWorkInsetMax;      // "

-    ImGuiViewportP()    { BgFgDrawListsLastFrame[0] = BgFgDrawListsLastFrame[1] = -1; BgFgDrawLists[0] = BgFgDrawLists[1] = NULL; }
-    ~ImGuiViewportP()   { if (BgFgDrawLists[0]) IM_DELETE(BgFgDrawLists[0]); if (BgFgDrawLists[1]) IM_DELETE(BgFgDrawLists[1]); }
+    ImGuiViewportP()                    { Window = NULL; Idx = -1; LastFrameActive = BgFgDrawListsLastFrame[0] = BgFgDrawListsLastFrame[1] = LastFocusedStampCount = -1; LastNameHash = 0; Alpha = LastAlpha = 1.0f; LastFocusedHadNavWindow = false; PlatformMonitor = -1; BgFgDrawLists[0] = BgFgDrawLists[1] = NULL; LastPlatformPos = LastPlatformSize = LastRendererSize = ImVec2(FLT_MAX, FLT_MAX); }
+    ~ImGuiViewportP()                   { if (BgFgDrawLists[0]) IM_DELETE(BgFgDrawLists[0]); if (BgFgDrawLists[1]) IM_DELETE(BgFgDrawLists[1]); }
+    void    ClearRequestFlags()         { PlatformRequestClose = PlatformRequestMove = PlatformRequestResize = false; }

    // Calculate work rect pos/size given a set of offset (we have 1 pair of offset for rect locked from last frame data, and 1 pair for currently building rect)
    ImVec2  CalcWorkRectPos(const ImVec2& inset_min) const                           { return ImVec2(Pos.x + inset_min.x, Pos.y + inset_min.y); }
@@ -1847,14 +2029,19 @@ struct ImGuiViewportP : public ImGuiViewport
 struct ImGuiWindowSettings
 {
    ImGuiID     ID;
-    ImVec2ih    Pos;
+    ImVec2ih    Pos;            // NB: Settings position are stored RELATIVE to the viewport! Whereas runtime ones are absolute positions.
    ImVec2ih    Size;
+    ImVec2ih    ViewportPos;
+    ImGuiID     ViewportId;
+    ImGuiID     DockId;         // ID of last known DockNode (even if the DockNode is invisible because it has only 1 active window), or 0 if none.
+    ImGuiID     ClassId;        // ID of window class if specified
+    short       DockOrder;      // Order of the last time the window was visible within its DockNode. This is used to reorder windows that are reappearing on the same frame. Same value between windows that were active and windows that were none are possible.
    bool        Collapsed;
    bool        IsChild;
    bool        WantApply;      // Set when loaded from .ini data (to enable merging/loading .ini data into an already running context)
    bool        WantDelete;     // Set to invalidate/delete the settings entry

-    ImGuiWindowSettings()       { memset(this, 0, sizeof(*this)); }
+    ImGuiWindowSettings()       { memset(this, 0, sizeof(*this)); DockOrder = -1; }
    char* GetName()             { return (char*)(this + 1); }
 };

@@ -1890,6 +2077,9 @@ enum ImGuiLocKey : int
    ImGuiLocKey_WindowingUntitled,
    ImGuiLocKey_OpenLink_s,
    ImGuiLocKey_CopyLink,
+    ImGuiLocKey_DockingHideTabBar,
+    ImGuiLocKey_DockingHoldShiftToDock,
+    ImGuiLocKey_DockingDragToUndockOrMoveNode,
    ImGuiLocKey_COUNT
 };

@@ -1932,8 +2122,8 @@ enum ImGuiDebugLogFlags_
    ImGuiDebugLogFlags_EventSelection       = 1 << 6,
    ImGuiDebugLogFlags_EventIO              = 1 << 7,
    ImGuiDebugLogFlags_EventInputRouting    = 1 << 8,
-    ImGuiDebugLogFlags_EventDocking         = 1 << 9,   // Unused in this branch
-    ImGuiDebugLogFlags_EventViewport        = 1 << 10,  // Unused in this branch
+    ImGuiDebugLogFlags_EventDocking         = 1 << 9,
+    ImGuiDebugLogFlags_EventViewport        = 1 << 10,

    ImGuiDebugLogFlags_EventMask_           = ImGuiDebugLogFlags_EventError | ImGuiDebugLogFlags_EventActiveId | ImGuiDebugLogFlags_EventFocus | ImGuiDebugLogFlags_EventPopup | ImGuiDebugLogFlags_EventNav | ImGuiDebugLogFlags_EventClipper | ImGuiDebugLogFlags_EventSelection | ImGuiDebugLogFlags_EventIO | ImGuiDebugLogFlags_EventInputRouting | ImGuiDebugLogFlags_EventDocking | ImGuiDebugLogFlags_EventViewport,
    ImGuiDebugLogFlags_OutputToTTY          = 1 << 20,  // Also send output to TTY
@@ -1968,6 +2158,7 @@ struct ImGuiMetricsConfig
    bool        ShowDrawCmdBoundingBoxes = true;
    bool        ShowTextEncodingViewer = false;
    bool        ShowAtlasTintedWithTextColor = false;
+    bool        ShowDockingNodes = false;
    int         ShowWindowsRectsType = -1;
    int         ShowTablesRectsType = -1;
    int         HighlightMonitorIdx = -1;
@@ -2027,15 +2218,18 @@ struct ImGuiContext
    ImGuiIO                 IO;
    ImGuiPlatformIO         PlatformIO;
    ImGuiStyle              Style;
+    ImGuiConfigFlags        ConfigFlagsCurrFrame;               // = g.IO.ConfigFlags at the time of NewFrame()
+    ImGuiConfigFlags        ConfigFlagsLastFrame;
    ImFont*                 Font;                               // (Shortcut) == FontStack.empty() ? IO.Font : FontStack.back()
    float                   FontSize;                           // (Shortcut) == FontBaseSize * g.CurrentWindow->FontWindowScale == window->FontSize(). Text height for current window.
    float                   FontBaseSize;                       // (Shortcut) == IO.FontGlobalScale * Font->Scale * Font->FontSize. Base text height.
    float                   FontScale;                          // == FontSize / Font->FontSize
-    float                   CurrentDpiScale;                    // Current window/viewport DpiScale
+    float                   CurrentDpiScale;                    // Current window/viewport DpiScale == CurrentViewport->DpiScale
    ImDrawListSharedData    DrawListSharedData;
    double                  Time;
    int                     FrameCount;
    int                     FrameCountEnded;
+    int                     FrameCountPlatformEnded;
    int                     FrameCountRendered;
    bool                    WithinFrameScope;                   // Set by NewFrame(), cleared by EndFrame()
    bool                    WithinFrameScopeWithImplicitWindow; // Set by NewFrame(), cleared by EndFrame() when the implicit debug window has been pushed
@@ -2064,7 +2258,7 @@ struct ImGuiContext
    ImGuiWindow*            HoveredWindow;                      // Window the mouse is hovering. Will typically catch mouse inputs.
    ImGuiWindow*            HoveredWindowUnderMovingWindow;     // Hovered window ignoring MovingWindow. Only set if MovingWindow is set.
    ImGuiWindow*            HoveredWindowBeforeClear;           // Window the mouse is hovering. Filled even with _NoMouse. This is currently useful for multi-context compositors.
-    ImGuiWindow*            MovingWindow;                       // Track the window we clicked on (in order to preserve focus). The actual window that is moved is generally MovingWindow->RootWindow.
+    ImGuiWindow*            MovingWindow;                       // Track the window we clicked on (in order to preserve focus). The actual window that is moved is generally MovingWindow->RootWindowDockTree.
    ImGuiWindow*            WheelingWindow;                     // Track the window we started mouse-wheeling on. Until a timer elapse or mouse has moved, generally keep scrolling the same window even if during the course of scrolling the mouse ends up hovering a child window.
    ImVec2                  WheelingWindowRefMousePos;
    int                     WheelingWindowStartFrame;           // This may be set one frame before WheelingWindow is != NULL
@@ -2142,7 +2336,16 @@ struct ImGuiContext
    ImVector<ImGuiTreeNodeStackData>TreeNodeStack;              // Stack for TreeNode()

    // Viewports
-    ImVector<ImGuiViewportP*> Viewports;                        // Active viewports (Size==1 in 'master' branch). Each viewports hold their copy of ImDrawData.
+    ImVector<ImGuiViewportP*> Viewports;                        // Active viewports (always 1+, and generally 1 unless multi-viewports are enabled). Each viewports hold their copy of ImDrawData.
+    ImGuiViewportP*         CurrentViewport;                    // We track changes of viewport (happening in Begin) so we can call Platform_OnChangedViewport()
+    ImGuiViewportP*         MouseViewport;
+    ImGuiViewportP*         MouseLastHoveredViewport;           // Last known viewport that was hovered by mouse (even if we are not hovering any viewport any more) + honoring the _NoInputs flag.
+    ImGuiID                 PlatformLastFocusedViewportId;
+    ImGuiPlatformMonitor    FallbackMonitor;                    // Virtual monitor used as fallback if backend doesn't provide monitor information.
+    ImRect                  PlatformMonitorsFullWorkRect;       // Bounding box of all platform monitors
+    int                     ViewportCreatedCount;               // Unique sequential creation counter (mostly for testing/debugging)
+    int                     PlatformWindowsCreatedCount;        // Unique sequential creation counter (mostly for testing/debugging)
+    int                     ViewportFocusedStampCount;          // Every time the front-most window changes, we stamp its viewport with an incrementing counter

    // Keyboard/Gamepad Navigation
    bool                    NavCursorVisible;                   // Nav focus cursor/rectangle is visible? We hide it after a mouse click. We show it after a nav move.
@@ -2312,6 +2515,12 @@ struct ImGuiContext
    // Platform support
    ImGuiPlatformImeData    PlatformImeData;                    // Data updated by current frame
    ImGuiPlatformImeData    PlatformImeDataPrev;                // Previous frame data. When changed we call the platform_io.Platform_SetImeDataFn() handler.
+    ImGuiID                 PlatformImeViewport;
+
+    // Extensions
+    // FIXME: We could provide an API to register one slot in an array held in ImGuiContext?
+    ImGuiDockContext        DockContext;
+    void                    (*DockNodeWindowMenuHandler)(ImGuiContext* ctx, ImGuiDockNode* node, ImGuiTabBar* tab_bar);

    // Settings
    bool                    SettingsLoaded;
@@ -2370,6 +2579,7 @@ struct ImGuiContext
    ImGuiMetricsConfig      DebugMetricsConfig;
    ImGuiIDStackTool        DebugIDStackTool;
    ImGuiDebugAllocInfo     DebugAllocInfo;
+    ImGuiDockNode*          DebugHoveredDockNode;               // Hovered dock node.

    // Misc
    float                   FramerateSecPerFrame[60];           // Calculate estimate of framerate for user over the last 60 frames..
@@ -2447,9 +2657,13 @@ struct IMGUI_API ImGuiWindow
    ImGuiContext*           Ctx;                                // Parent UI context (needs to be set explicitly by parent).
    char*                   Name;                               // Window name, owned by the window.
    ImGuiID                 ID;                                 // == ImHashStr(Name)
-    ImGuiWindowFlags        Flags;                              // See enum ImGuiWindowFlags_
+    ImGuiWindowFlags        Flags, FlagsPreviousFrame;          // See enum ImGuiWindowFlags_
    ImGuiChildFlags         ChildFlags;                         // Set when window is a child window. See enum ImGuiChildFlags_
+    ImGuiWindowClass        WindowClass;                        // Advanced users only. Set with SetNextWindowClass()
    ImGuiViewportP*         Viewport;                           // Always set in Begin(). Inactive windows may have a NULL value here if their viewport was discarded.
+    ImGuiID                 ViewportId;                         // We backup the viewport id (since the viewport may disappear or never be created if the window is inactive)
+    ImVec2                  ViewportPos;                        // We backup the viewport position (since the viewport may disappear or never be created if the window is inactive)
+    int                     ViewportAllowPlatformMonitorExtend; // Reset to -1 every frame (index is guaranteed to be valid between NewFrame..EndFrame), only used in the Appearing frame of a tooltip/popup to enforce clamping to a given monitor
    ImVec2                  Pos;                                // Position (always rounded-up to nearest pixel)
    ImVec2                  Size;                               // Current size (==SizeFull or collapsed title bar size)
    ImVec2                  SizeFull;                           // Size when non collapsed
@@ -2465,6 +2679,7 @@ struct IMGUI_API ImGuiWindow
    float                   DecoInnerSizeX1, DecoInnerSizeY1;   // Applied AFTER/OVER InnerRect. Specialized for Tables as they use specialized form of clipping and frozen rows/columns are inside InnerRect (and not part of regular decoration sizes).
    int                     NameBufLen;                         // Size of buffer storing Name. May be larger than strlen(Name)!
    ImGuiID                 MoveId;                             // == window->GetID("#MOVE")
+    ImGuiID                 TabId;                              // == window->GetID("#TAB")
    ImGuiID                 ChildId;                            // ID of corresponding item in parent window (for navigation to return from child window to parent window)
    ImGuiID                 PopupId;                            // ID in the popup stack when this window is used as a popup/menu (because we use generic Name/ID for recycling)
    ImVec2                  Scroll;
@@ -2474,6 +2689,7 @@ struct IMGUI_API ImGuiWindow
    ImVec2                  ScrollTargetEdgeSnapDist;           // 0.0f = no snapping, >0.0f snapping threshold
    ImVec2                  ScrollbarSizes;                     // Size taken by each scrollbars on their smaller axis. Pay attention! ScrollbarSizes.x == width of the vertical scrollbar, ScrollbarSizes.y = height of the horizontal scrollbar.
    bool                    ScrollbarX, ScrollbarY;             // Are scrollbars visible?
+    bool                    ViewportOwned;
    bool                    Active;                             // Set to true on Begin(), unless Collapsed
    bool                    WasActive;
    bool                    WriteAccessed;                      // Set to true when any widget access the current window
@@ -2503,6 +2719,7 @@ struct IMGUI_API ImGuiWindow
    ImGuiCond               SetWindowPosAllowFlags : 8;         // store acceptable condition flags for SetNextWindowPos() use.
    ImGuiCond               SetWindowSizeAllowFlags : 8;        // store acceptable condition flags for SetNextWindowSize() use.
    ImGuiCond               SetWindowCollapsedAllowFlags : 8;   // store acceptable condition flags for SetNextWindowCollapsed() use.
+    ImGuiCond               SetWindowDockAllowFlags : 8;        // store acceptable condition flags for SetNextWindowDock() use.
    ImVec2                  SetWindowPosVal;                    // store window position when using a non-zero Pivot (position set needs to be processed when we know the window size)
    ImVec2                  SetWindowPosPivot;                  // store window pivot for positioning. ImVec2(0, 0) when positioning from top-left corner; ImVec2(0.5f, 0.5f) for centering; ImVec2(1, 1) for bottom right.

@@ -2522,11 +2739,13 @@ struct IMGUI_API ImGuiWindow
    ImVec2ih                HitTestHoleOffset;

    int                     LastFrameActive;                    // Last frame number the window was Active.
+    int                     LastFrameJustFocused;               // Last frame number the window was made Focused.
    float                   LastTimeActive;                     // Last timestamp the window was Active (using float as we don't need high precision there)
    float                   ItemWidthDefault;
    ImGuiStorage            StateStorage;
    ImVector<ImGuiOldColumns> ColumnsStorage;
    float                   FontWindowScale;                    // User scale multiplier per-window, via SetWindowFontScale()
+    float                   FontDpiScale;
    int                     SettingsOffset;                     // Offset into SettingsWindows[] (offsets are always valid as we only grow the array from the back)

    ImDrawList*             DrawList;                           // == &DrawListInst (for backward compatibility reason with code using imgui_internal.h we keep this a pointer)
@@ -2535,6 +2754,7 @@ struct IMGUI_API ImGuiWindow
    ImGuiWindow*            ParentWindowInBeginStack;
    ImGuiWindow*            RootWindow;                         // Point to ourself or first ancestor that is not a child window. Doesn't cross through popups/dock nodes.
    ImGuiWindow*            RootWindowPopupTree;                // Point to ourself or first ancestor that is not a child window. Cross through popups parent<>child.
+    ImGuiWindow*            RootWindowDockTree;                 // Point to ourself or first ancestor that is not a child window. Cross through dock nodes.
    ImGuiWindow*            RootWindowForTitleBarHighlight;     // Point to ourself or first ancestor which will display TitleBgActive color when this window is active.
    ImGuiWindow*            RootWindowForNav;                   // Point to ourself or first ancestor which doesn't have the NavFlattened flag.
    ImGuiWindow*            ParentWindowForFocusRoute;          // Set to manual link a window to its logical parent so that Shortcut() chain are honoerd (e.g. Tool linked to Document)
@@ -2549,6 +2769,19 @@ struct IMGUI_API ImGuiWindow
    int                     MemoryDrawListVtxCapacity;
    bool                    MemoryCompacted;                    // Set when window extraneous data have been garbage collected

+    // Docking
+    bool                    DockIsActive        :1;             // When docking artifacts are actually visible. When this is set, DockNode is guaranteed to be != NULL. ~~ (DockNode != NULL) && (DockNode->Windows.Size > 1).
+    bool                    DockNodeIsVisible   :1;
+    bool                    DockTabIsVisible    :1;             // Is our window visible this frame? ~~ is the corresponding tab selected?
+    bool                    DockTabWantClose    :1;
+    short                   DockOrder;                          // Order of the last time the window was visible within its DockNode. This is used to reorder windows that are reappearing on the same frame. Same value between windows that were active and windows that were none are possible.
+    ImGuiWindowDockStyle    DockStyle;
+    ImGuiDockNode*          DockNode;                           // Which node are we docked into. Important: Prefer testing DockIsActive in many cases as this will still be set when the dock node is hidden.
+    ImGuiDockNode*          DockNodeAsHost;                     // Which node are we owning (for parent windows)
+    ImGuiID                 DockId;                             // Backup of last valid DockNode->ID, so single window remember their dock node id even when they are not bound any more
+    ImGuiItemStatusFlags    DockTabItemStatusFlags;
+    ImRect                  DockTabItemRect;
+
 public:
    ImGuiWindow(ImGuiContext* context, const char* name);
    ~ImGuiWindow();
@@ -2561,7 +2794,7 @@ public:

    // We don't use g.FontSize because the window may be != g.CurrentWindow.
    ImRect      Rect() const            { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
-    float       CalcFontSize() const    { ImGuiContext& g = *Ctx; float scale = g.FontBaseSize * FontWindowScale; if (ParentWindow) scale *= ParentWindow->FontWindowScale; return scale; }
+    float       CalcFontSize() const    { ImGuiContext& g = *Ctx; float scale = g.FontBaseSize * FontWindowScale * FontDpiScale; if (ParentWindow) scale *= ParentWindow->FontWindowScale; return scale; }
    ImRect      TitleBarRect() const    { return ImRect(Pos, ImVec2(Pos.x + SizeFull.x, Pos.y + TitleBarHeight)); }
    ImRect      MenuBarRect() const     { float y1 = Pos.y + TitleBarHeight; return ImRect(Pos.x, y1, Pos.x + SizeFull.x, y1 + MenuBarHeight); }
 };
@@ -2584,13 +2817,15 @@ enum ImGuiTabItemFlagsPrivate_
    ImGuiTabItemFlags_SectionMask_              = ImGuiTabItemFlags_Leading | ImGuiTabItemFlags_Trailing,
    ImGuiTabItemFlags_NoCloseButton             = 1 << 20,  // Track whether p_open was set or not (we'll need this info on the next frame to recompute ContentWidth during layout)
    ImGuiTabItemFlags_Button                    = 1 << 21,  // Used by TabItemButton, change the tab item behavior to mimic a button
+    ImGuiTabItemFlags_Unsorted                  = 1 << 22,  // [Docking] Trailing tabs with the _Unsorted flag will be sorted based on the DockOrder of their Window.
 };

-// Storage for one active tab item (sizeof() 40 bytes)
+// Storage for one active tab item (sizeof() 48 bytes)
 struct ImGuiTabItem
 {
    ImGuiID             ID;
    ImGuiTabItemFlags   Flags;
+    ImGuiWindow*        Window;                 // When TabItem is part of a DockNode's TabBar, we hold on to a window.
    int                 LastFrameVisible;
    int                 LastFrameSelected;      // This allows us to infer an ordered list of the last activated tabs with little maintenance
    float               Offset;                 // Position relative to beginning of tab
@@ -2957,7 +3192,7 @@ namespace ImGui
    IMGUI_API void          UpdateWindowParentAndRootLinks(ImGuiWindow* window, ImGuiWindowFlags flags, ImGuiWindow* parent_window);
    IMGUI_API void          UpdateWindowSkipRefresh(ImGuiWindow* window);
    IMGUI_API ImVec2        CalcWindowNextAutoFitSize(ImGuiWindow* window);
-    IMGUI_API bool          IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent, bool popup_hierarchy);
+    IMGUI_API bool          IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent, bool popup_hierarchy, bool dock_hierarchy);
    IMGUI_API bool          IsWindowWithinBeginStackOf(ImGuiWindow* window, ImGuiWindow* potential_parent);
    IMGUI_API bool          IsWindowAbove(ImGuiWindow* potential_above, ImGuiWindow* potential_below);
    IMGUI_API bool          IsWindowNavFocusable(ImGuiWindow* window);
@@ -2966,7 +3201,7 @@ namespace ImGui
    IMGUI_API void          SetWindowCollapsed(ImGuiWindow* window, bool collapsed, ImGuiCond cond = 0);
    IMGUI_API void          SetWindowHitTestHole(ImGuiWindow* window, const ImVec2& pos, const ImVec2& size);
    IMGUI_API void          SetWindowHiddenAndSkipItemsForCurrentFrame(ImGuiWindow* window);
-    inline void             SetWindowParentWindowForFocusRoute(ImGuiWindow* window, ImGuiWindow* parent_window) { window->ParentWindowForFocusRoute = parent_window; }
+    inline void             SetWindowParentWindowForFocusRoute(ImGuiWindow* window, ImGuiWindow* parent_window) { window->ParentWindowForFocusRoute = parent_window; } // You may also use SetNextWindowClass()'s FocusRouteParentWindowId field.
    inline ImRect           WindowRectAbsToRel(ImGuiWindow* window, const ImRect& r) { ImVec2 off = window->DC.CursorStartPos; return ImRect(r.Min.x - off.x, r.Min.y - off.y, r.Max.x - off.x, r.Max.y - off.y); }
    inline ImRect           WindowRectRelToAbs(ImGuiWindow* window, const ImRect& r) { ImVec2 off = window->DC.CursorStartPos; return ImRect(r.Min.x + off.x, r.Min.y + off.y, r.Max.x + off.x, r.Max.y + off.y); }
    inline ImVec2           WindowPosAbsToRel(ImGuiWindow* window, const ImVec2& p)  { ImVec2 off = window->DC.CursorStartPos; return ImVec2(p.x - off.x, p.y - off.y); }
@@ -2988,9 +3223,7 @@ namespace ImGui
    // Fonts, drawing
    IMGUI_API void          SetCurrentFont(ImFont* font);
    inline ImFont*          GetDefaultFont() { ImGuiContext& g = *GImGui; return g.IO.FontDefault ? g.IO.FontDefault : g.IO.Fonts->Fonts[0]; }
-    inline ImDrawList*      GetForegroundDrawList(ImGuiWindow* window) { IM_UNUSED(window); return GetForegroundDrawList(); } // This seemingly unnecessary wrapper simplifies compatibility between the 'master' and 'docking' branches.
-    IMGUI_API ImDrawList*   GetBackgroundDrawList(ImGuiViewport* viewport);                     // get background draw list for the given viewport. this draw list will be the first rendering one. Useful to quickly draw shapes/text behind dear imgui contents.
-    IMGUI_API ImDrawList*   GetForegroundDrawList(ImGuiViewport* viewport);                     // get foreground draw list for the given viewport. this draw list will be the last rendered one. Useful to quickly draw shapes/text over dear imgui contents.
+    inline ImDrawList*      GetForegroundDrawList(ImGuiWindow* window) { return GetForegroundDrawList(window->Viewport); }
    IMGUI_API void          AddDrawListToDrawDataEx(ImDrawData* draw_data, ImVector<ImDrawList*>* out_list, ImDrawList* draw_list);

    // Init
@@ -3002,6 +3235,7 @@ namespace ImGui
    IMGUI_API void          UpdateHoveredWindowAndCaptureFlags();
    IMGUI_API void          FindHoveredWindowEx(const ImVec2& pos, bool find_first_and_in_any_viewport, ImGuiWindow** out_hovered_window, ImGuiWindow** out_hovered_window_under_moving_window);
    IMGUI_API void          StartMouseMovingWindow(ImGuiWindow* window);
+    IMGUI_API void          StartMouseMovingWindowOrNode(ImGuiWindow* window, ImGuiDockNode* node, bool undock);
    IMGUI_API void          UpdateMouseMovingWindowNewFrame();
    IMGUI_API void          UpdateMouseMovingWindowEndFrame();

@@ -3011,7 +3245,13 @@ namespace ImGui
    IMGUI_API void          CallContextHooks(ImGuiContext* context, ImGuiContextHookType type);

    // Viewports
+    IMGUI_API void          TranslateWindowsInViewport(ImGuiViewportP* viewport, const ImVec2& old_pos, const ImVec2& new_pos, const ImVec2& old_size, const ImVec2& new_size);
+    IMGUI_API void          ScaleWindowsInViewport(ImGuiViewportP* viewport, float scale);
+    IMGUI_API void          DestroyPlatformWindow(ImGuiViewportP* viewport);
    IMGUI_API void          SetWindowViewport(ImGuiWindow* window, ImGuiViewportP* viewport);
+    IMGUI_API void          SetCurrentViewport(ImGuiWindow* window, ImGuiViewportP* viewport);
+    IMGUI_API const ImGuiPlatformMonitor*   GetViewportPlatformMonitor(ImGuiViewport* viewport);
+    IMGUI_API ImGuiViewportP*               FindHoveredViewportFromPlatformWindowStack(const ImVec2& mouse_platform_pos);

    // Settings
    IMGUI_API void                  MarkIniSettingsDirty();
@@ -3226,6 +3466,61 @@ namespace ImGui
    IMGUI_API bool          TestShortcutRouting(ImGuiKeyChord key_chord, ImGuiID owner_id);
    IMGUI_API ImGuiKeyRoutingData* GetShortcutRoutingData(ImGuiKeyChord key_chord);

+    // Docking
+    // (some functions are only declared in imgui.cpp, see Docking section)
+    IMGUI_API void          DockContextInitialize(ImGuiContext* ctx);
+    IMGUI_API void          DockContextShutdown(ImGuiContext* ctx);
+    IMGUI_API void          DockContextClearNodes(ImGuiContext* ctx, ImGuiID root_id, bool clear_settings_refs); // Use root_id==0 to clear all
+    IMGUI_API void          DockContextRebuildNodes(ImGuiContext* ctx);
+    IMGUI_API void          DockContextNewFrameUpdateUndocking(ImGuiContext* ctx);
+    IMGUI_API void          DockContextNewFrameUpdateDocking(ImGuiContext* ctx);
+    IMGUI_API void          DockContextEndFrame(ImGuiContext* ctx);
+    IMGUI_API ImGuiID       DockContextGenNodeID(ImGuiContext* ctx);
+    IMGUI_API void          DockContextQueueDock(ImGuiContext* ctx, ImGuiWindow* target, ImGuiDockNode* target_node, ImGuiWindow* payload, ImGuiDir split_dir, float split_ratio, bool split_outer);
+    IMGUI_API void          DockContextQueueUndockWindow(ImGuiContext* ctx, ImGuiWindow* window);
+    IMGUI_API void          DockContextQueueUndockNode(ImGuiContext* ctx, ImGuiDockNode* node);
+    IMGUI_API void          DockContextProcessUndockWindow(ImGuiContext* ctx, ImGuiWindow* window, bool clear_persistent_docking_ref = true);
+    IMGUI_API void          DockContextProcessUndockNode(ImGuiContext* ctx, ImGuiDockNode* node);
+    IMGUI_API bool          DockContextCalcDropPosForDocking(ImGuiWindow* target, ImGuiDockNode* target_node, ImGuiWindow* payload_window, ImGuiDockNode* payload_node, ImGuiDir split_dir, bool split_outer, ImVec2* out_pos);
+    IMGUI_API ImGuiDockNode*DockContextFindNodeByID(ImGuiContext* ctx, ImGuiID id);
+    IMGUI_API void          DockNodeWindowMenuHandler_Default(ImGuiContext* ctx, ImGuiDockNode* node, ImGuiTabBar* tab_bar);
+    IMGUI_API bool          DockNodeBeginAmendTabBar(ImGuiDockNode* node);
+    IMGUI_API void          DockNodeEndAmendTabBar();
+    inline ImGuiDockNode*   DockNodeGetRootNode(ImGuiDockNode* node)                 { while (node->ParentNode) node = node->ParentNode; return node; }
+    inline bool             DockNodeIsInHierarchyOf(ImGuiDockNode* node, ImGuiDockNode* parent) { while (node) { if (node == parent) return true; node = node->ParentNode; } return false; }
+    inline int              DockNodeGetDepth(const ImGuiDockNode* node)              { int depth = 0; while (node->ParentNode) { node = node->ParentNode; depth++; } return depth; }
+    inline ImGuiID          DockNodeGetWindowMenuButtonId(const ImGuiDockNode* node) { return ImHashStr("#COLLAPSE", 0, node->ID); }
+    inline ImGuiDockNode*   GetWindowDockNode()                                      { ImGuiContext& g = *GImGui; return g.CurrentWindow->DockNode; }
+    IMGUI_API bool          GetWindowAlwaysWantOwnTabBar(ImGuiWindow* window);
+    IMGUI_API void          BeginDocked(ImGuiWindow* window, bool* p_open);
+    IMGUI_API void          BeginDockableDragDropSource(ImGuiWindow* window);
+    IMGUI_API void          BeginDockableDragDropTarget(ImGuiWindow* window);
+    IMGUI_API void          SetWindowDock(ImGuiWindow* window, ImGuiID dock_id, ImGuiCond cond);
+
+    // Docking - Builder function needs to be generally called before the node is used/submitted.
+    // - The DockBuilderXXX functions are designed to _eventually_ become a public API, but it is too early to expose it and guarantee stability.
+    // - Do not hold on ImGuiDockNode* pointers! They may be invalidated by any split/merge/remove operation and every frame.
+    // - To create a DockSpace() node, make sure to set the ImGuiDockNodeFlags_DockSpace flag when calling DockBuilderAddNode().
+    //   You can create dockspace nodes (attached to a window) _or_ floating nodes (carry its own window) with this API.
+    // - DockBuilderSplitNode() create 2 child nodes within 1 node. The initial node becomes a parent node.
+    // - If you intend to split the node immediately after creation using DockBuilderSplitNode(), make sure
+    //   to call DockBuilderSetNodeSize() beforehand. If you don't, the resulting split sizes may not be reliable.
+    // - Call DockBuilderFinish() after you are done.
+    IMGUI_API void          DockBuilderDockWindow(const char* window_name, ImGuiID node_id);
+    IMGUI_API ImGuiDockNode*DockBuilderGetNode(ImGuiID node_id);
+    inline ImGuiDockNode*   DockBuilderGetCentralNode(ImGuiID node_id)              { ImGuiDockNode* node = DockBuilderGetNode(node_id); if (!node) return NULL; return DockNodeGetRootNode(node)->CentralNode; }
+    IMGUI_API ImGuiID       DockBuilderAddNode(ImGuiID node_id = 0, ImGuiDockNodeFlags flags = 0);
+    IMGUI_API void          DockBuilderRemoveNode(ImGuiID node_id);                 // Remove node and all its child, undock all windows
+    IMGUI_API void          DockBuilderRemoveNodeDockedWindows(ImGuiID node_id, bool clear_settings_refs = true);
+    IMGUI_API void          DockBuilderRemoveNodeChildNodes(ImGuiID node_id);       // Remove all split/hierarchy. All remaining docked windows will be re-docked to the remaining root node (node_id).
+    IMGUI_API void          DockBuilderSetNodePos(ImGuiID node_id, ImVec2 pos);
+    IMGUI_API void          DockBuilderSetNodeSize(ImGuiID node_id, ImVec2 size);
+    IMGUI_API ImGuiID       DockBuilderSplitNode(ImGuiID node_id, ImGuiDir split_dir, float size_ratio_for_node_at_dir, ImGuiID* out_id_at_dir, ImGuiID* out_id_at_opposite_dir); // Create 2 child nodes in this parent node.
+    IMGUI_API void          DockBuilderCopyDockSpace(ImGuiID src_dockspace_id, ImGuiID dst_dockspace_id, ImVector<const char*>* in_window_remap_pairs);
+    IMGUI_API void          DockBuilderCopyNode(ImGuiID src_node_id, ImGuiID dst_node_id, ImVector<ImGuiID>* out_node_remap_pairs);
+    IMGUI_API void          DockBuilderCopyWindowSettings(const char* src_name, const char* dst_name);
+    IMGUI_API void          DockBuilderFinish(ImGuiID node_id);
+
    // [EXPERIMENTAL] Focus Scope
    // This is generally used to identify a unique input location (for e.g. a selection set)
    // There is one per window (automatically set in Begin), but:
@@ -3338,9 +3633,11 @@ namespace ImGui
    IMGUI_API bool          BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& bb, ImGuiTabBarFlags flags);
    IMGUI_API ImGuiTabItem* TabBarFindTabByID(ImGuiTabBar* tab_bar, ImGuiID tab_id);
    IMGUI_API ImGuiTabItem* TabBarFindTabByOrder(ImGuiTabBar* tab_bar, int order);
+    IMGUI_API ImGuiTabItem* TabBarFindMostRecentlySelectedTabForActiveWindow(ImGuiTabBar* tab_bar);
    IMGUI_API ImGuiTabItem* TabBarGetCurrentTab(ImGuiTabBar* tab_bar);
    inline int              TabBarGetTabOrder(ImGuiTabBar* tab_bar, ImGuiTabItem* tab) { return tab_bar->Tabs.index_from_ptr(tab); }
    IMGUI_API const char*   TabBarGetTabName(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
+    IMGUI_API void          TabBarAddTab(ImGuiTabBar* tab_bar, ImGuiTabItemFlags tab_flags, ImGuiWindow* window);
    IMGUI_API void          TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id);
    IMGUI_API void          TabBarCloseTab(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
    IMGUI_API void          TabBarQueueFocus(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
@@ -3377,8 +3674,10 @@ namespace ImGui
    IMGUI_API void          RenderBullet(ImDrawList* draw_list, ImVec2 pos, ImU32 col);
    IMGUI_API void          RenderCheckMark(ImDrawList* draw_list, ImVec2 pos, ImU32 col, float sz);
    IMGUI_API void          RenderArrowPointingAt(ImDrawList* draw_list, ImVec2 pos, ImVec2 half_sz, ImGuiDir direction, ImU32 col);
+    IMGUI_API void          RenderArrowDockMenu(ImDrawList* draw_list, ImVec2 p_min, float sz, ImU32 col);
    IMGUI_API void          RenderRectFilledRangeH(ImDrawList* draw_list, const ImRect& rect, ImU32 col, float x_start_norm, float x_end_norm, float rounding);
    IMGUI_API void          RenderRectFilledWithHole(ImDrawList* draw_list, const ImRect& outer, const ImRect& inner, ImU32 col, float rounding);
+    IMGUI_API ImDrawFlags   CalcRoundingFlagsForRectInRect(const ImRect& r_in, const ImRect& r_outer, float threshold);

    // Widgets
    IMGUI_API void          TextEx(const char* text, const char* text_end = NULL, ImGuiTextFlags flags = 0);
@@ -3392,7 +3691,7 @@ namespace ImGui

    // Widgets: Window Decorations
    IMGUI_API bool          CloseButton(ImGuiID id, const ImVec2& pos);
-    IMGUI_API bool          CollapseButton(ImGuiID id, const ImVec2& pos);
+    IMGUI_API bool          CollapseButton(ImGuiID id, const ImVec2& pos, ImGuiDockNode* dock_node);
    IMGUI_API void          Scrollbar(ImGuiAxis axis);
    IMGUI_API bool          ScrollbarEx(const ImRect& bb, ImGuiID id, ImGuiAxis axis, ImS64* p_scroll_v, ImS64 avail_v, ImS64 contents_v, ImDrawFlags flags);
    IMGUI_API ImRect        GetWindowScrollbarRect(ImGuiWindow* window, ImGuiAxis axis);
@@ -3484,6 +3783,7 @@ namespace ImGui
    IMGUI_API void          ShowFontAtlas(ImFontAtlas* atlas);
    IMGUI_API void          DebugHookIdInfo(ImGuiID id, ImGuiDataType data_type, const void* data_id, const void* data_id_end);
    IMGUI_API void          DebugNodeColumns(ImGuiOldColumns* columns);
+    IMGUI_API void          DebugNodeDockNode(ImGuiDockNode* node, const char* label);
    IMGUI_API void          DebugNodeDrawList(ImGuiWindow* window, ImGuiViewportP* viewport, const ImDrawList* draw_list, const char* label);
    IMGUI_API void          DebugNodeDrawCmdShowMeshAndBoundingBox(ImDrawList* out_draw_list, const ImDrawList* draw_list, const ImDrawCmd* draw_cmd, bool show_mesh, bool show_aabb);
    IMGUI_API void          DebugNodeFont(ImFont* font);
@@ -3500,6 +3800,7 @@ namespace ImGui
    IMGUI_API void          DebugNodeWindowsList(ImVector<ImGuiWindow*>* windows, const char* label);
    IMGUI_API void          DebugNodeWindowsListByBeginStackParent(ImGuiWindow** windows, int windows_size, ImGuiWindow* parent_in_begin_stack);
    IMGUI_API void          DebugNodeViewport(ImGuiViewportP* viewport);
+    IMGUI_API void          DebugNodePlatformMonitor(ImGuiPlatformMonitor* monitor, const char* label, int idx);
    IMGUI_API void          DebugRenderKeyboardPreview(ImDrawList* draw_list);
    IMGUI_API void          DebugRenderViewportThumbnail(ImDrawList* draw_list, ImGuiViewportP* viewport, const ImRect& bb);

@@ -511,7 +511,7 @@ bool ImGui::ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool
        flags |= (item_flags & ImGuiItemFlags_ButtonRepeat) ? ImGuiButtonFlags_PressedOnClick : ImGuiButtonFlags_PressedOnDefault_;

    ImGuiWindow* backup_hovered_window = g.HoveredWindow;
-    const bool flatten_hovered_children = (flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredWindow && g.HoveredWindow->RootWindow == window;
+    const bool flatten_hovered_children = (flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredWindow && g.HoveredWindow->RootWindowDockTree == window->RootWindowDockTree;
    if (flatten_hovered_children)
        g.HoveredWindow = window;

@@ -869,7 +869,8 @@ bool ImGui::CloseButton(ImGuiID id, const ImVec2& pos)
    return pressed;
 }

-bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos)
+// The Collapse button also functions as a Dock Menu button.
+bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos, ImGuiDockNode* dock_node)
 {
    ImGuiContext& g = *GImGui;
    ImGuiWindow* window = g.CurrentWindow;
@@ -882,16 +883,21 @@ bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos)
        return pressed;

    // Render
+    //bool is_dock_menu = (window->DockNodeAsHost && !window->Collapsed);
    ImU32 bg_col = GetColorU32((held && hovered) ? ImGuiCol_ButtonActive : hovered ? ImGuiCol_ButtonHovered : ImGuiCol_Button);
    ImU32 text_col = GetColorU32(ImGuiCol_Text);
    if (hovered || held)
        window->DrawList->AddRectFilled(bb.Min, bb.Max, bg_col);
    RenderNavCursor(bb, id, ImGuiNavRenderCursorFlags_Compact);
-    RenderArrow(window->DrawList, bb.Min, text_col, window->Collapsed ? ImGuiDir_Right : ImGuiDir_Down, 1.0f);
+
+    if (dock_node)
+        RenderArrowDockMenu(window->DrawList, bb.Min, g.FontSize, text_col);
+    else
+        RenderArrow(window->DrawList, bb.Min, text_col, window->Collapsed ? ImGuiDir_Right : ImGuiDir_Down, 1.0f);

    // Switch to moving the window after mouse is moved beyond the initial drag threshold
    if (IsItemActive() && IsMouseDragging(0))
-        StartMouseMovingWindow(window);
+        StartMouseMovingWindowOrNode(window, dock_node, true); // Undock from window/collapse menu button

    return pressed;
 }
@@ -1634,7 +1640,7 @@ void ImGui::SeparatorTextEx(ImGuiID id, const char* label, const char* label_end
    const float separator_thickness = style.SeparatorTextBorderSize;
    const ImVec2 min_size(label_size.x + extra_w + padding.x * 2.0f, ImMax(label_size.y + padding.y * 2.0f, separator_thickness));
    const ImRect bb(pos, ImVec2(window->WorkRect.Max.x, pos.y + min_size.y));
-    const float text_baseline_y = ImTrunc((bb.GetHeight() - label_size.y) * style.SeparatorTextAlign.y + 0.99999f); //ImMax(padding.y, ImFloor((style.SeparatorTextSize - label_size.y) * 0.5f));
+    const float text_baseline_y = ImTrunc((bb.GetHeight() - label_size.y) * style.SeparatorTextAlign.y + 0.99999f); //ImMax(padding.y, ImTrunc((style.SeparatorTextSize - label_size.y) * 0.5f));
    ItemSize(min_size, text_baseline_y);
    if (!ItemAdd(bb, id))
        return;
@@ -1862,11 +1868,11 @@ bool ImGui::BeginCombo(const char* label, const char* preview_value, ImGuiComboF
        window->DrawList->AddRectFilled(bb.Min, ImVec2(value_x2, bb.Max.y), frame_col, style.FrameRounding, (flags & ImGuiComboFlags_NoArrowButton) ? ImDrawFlags_RoundCornersAll : ImDrawFlags_RoundCornersLeft);
    if (!(flags & ImGuiComboFlags_NoArrowButton))
    {
-        ImU32 bg_col = GetColorU32((popup_open || hovered) ? ImGuiCol_ButtonHovered : ImGuiCol_Button);
+        // Frame Studio: the arrow is a small one on the field itself (no separate button), as the other dropdowns
        ImU32 text_col = GetColorU32(ImGuiCol_Text);
-        window->DrawList->AddRectFilled(ImVec2(value_x2, bb.Min.y), bb.Max, bg_col, style.FrameRounding, (w <= arrow_size) ? ImDrawFlags_RoundCornersAll : ImDrawFlags_RoundCornersRight);
+        window->DrawList->AddRectFilled(ImVec2(value_x2, bb.Min.y), bb.Max, frame_col, style.FrameRounding, (w <= arrow_size) ? ImDrawFlags_RoundCornersAll : ImDrawFlags_RoundCornersRight);
        if (value_x2 + arrow_size - style.FramePadding.x <= bb.Max.x)
-            RenderArrow(window->DrawList, ImVec2(value_x2 + style.FramePadding.y, bb.Min.y + style.FramePadding.y), text_col, ImGuiDir_Down, 1.0f);
+            RenderArrow(window->DrawList, ImVec2(value_x2 + (arrow_size - g.FontSize * 0.55f) * 0.5f, bb.Min.y + (bb.GetHeight() - g.FontSize * 0.55f) * 0.5f), text_col, ImGuiDir_Down, 0.55f);
    }
    RenderFrameBorder(bb.Min, bb.Max, style.FrameRounding);

@@ -5272,6 +5278,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
                g.PlatformImeData.WantVisible = true;
                g.PlatformImeData.InputPos = ImVec2(cursor_screen_pos.x - 1.0f, cursor_screen_pos.y - g.FontSize);
                g.PlatformImeData.InputLineHeight = g.FontSize;
+                g.PlatformImeViewport = window->Viewport->ID;
            }
        }
    }
@@ -8588,7 +8595,7 @@ bool ImGui::BeginMenuBar()
    // We don't clip with current window clipping rectangle as it is already set to the area below. However we clip with window full rect.
    // We remove 1 worth of rounding to Max.x to that text in long menus and small windows don't tend to display over the lower-right rounded area, which looks particularly glitchy.
    ImRect bar_rect = window->MenuBarRect();
-    ImRect clip_rect(IM_ROUND(bar_rect.Min.x + window->WindowBorderSize), IM_ROUND(bar_rect.Min.y + window->WindowBorderSize), IM_ROUND(ImMax(bar_rect.Min.x, bar_rect.Max.x - ImMax(window->WindowRounding, window->WindowBorderSize))), IM_ROUND(bar_rect.Max.y));
+    ImRect clip_rect(ImFloor(bar_rect.Min.x + window->WindowBorderSize), ImFloor(bar_rect.Min.y + window->WindowBorderSize), ImFloor(ImMax(bar_rect.Min.x, bar_rect.Max.x - ImMax(window->WindowRounding, window->WindowBorderSize))), ImFloor(bar_rect.Max.y));
    clip_rect.ClipWith(window->OuterRectClipped);
    PushClipRect(clip_rect.Min, clip_rect.Max, false);

@@ -8663,10 +8670,10 @@ bool ImGui::BeginViewportSideBar(const char* name, ImGuiViewport* viewport_p, Im
    IM_ASSERT(dir != ImGuiDir_None);

    ImGuiWindow* bar_window = FindWindowByName(name);
+    ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)(viewport_p ? viewport_p : GetMainViewport());
    if (bar_window == NULL || bar_window->BeginCount == 0)
    {
        // Calculate and set window size/position
-        ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)(viewport_p ? viewport_p : GetMainViewport());
        ImRect avail_rect = viewport->GetBuildWorkRect();
        ImGuiAxis axis = (dir == ImGuiDir_Up || dir == ImGuiDir_Down) ? ImGuiAxis_Y : ImGuiAxis_X;
        ImVec2 pos = avail_rect.Min;
@@ -8684,7 +8691,8 @@ bool ImGui::BeginViewportSideBar(const char* name, ImGuiViewport* viewport_p, Im
            viewport->BuildWorkInsetMax[axis] += axis_size;
    }

-    window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove;
+    window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoDocking;
+    SetNextWindowViewport(viewport->ID); // Enforce viewport so we don't create our own viewport when ImGuiConfigFlags_ViewportsNoMerge is set.
    PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
    PushStyleVar(ImGuiStyleVar_WindowMinSize, ImVec2(0, 0)); // Lift normal size constraint
    bool is_open = Begin(name, NULL, window_flags);
@@ -8698,6 +8706,9 @@ bool ImGui::BeginMainMenuBar()
    ImGuiContext& g = *GImGui;
    ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)GetMainViewport();

+    // Notify of viewport change so GetFrameHeight() can be accurate in case of DPI change
+    SetCurrentViewport(NULL, viewport);
+
    // For the main menu bar, which cannot be moved, we honor g.Style.DisplaySafeAreaPadding to ensure text can be visible on a TV set.
    // FIXME: This could be generalized as an opt-in way to clamp window->DC.CursorStartPos to avoid SafeArea?
    // FIXME: Consider removing support for safe area down the line... it's messy. Nowadays consoles have support for TV calibration in OS settings.
@@ -8748,7 +8759,7 @@ static bool IsRootOfOpenMenuSet()
    const ImGuiPopupData* upper_popup = &g.OpenPopupStack[g.BeginPopupStack.Size];
    if (window->DC.NavLayerCurrent != upper_popup->ParentNavLayer)
        return false;
-    return upper_popup->Window && (upper_popup->Window->Flags & ImGuiWindowFlags_ChildMenu) && ImGui::IsWindowChildOf(upper_popup->Window, window, true);
+    return upper_popup->Window && (upper_popup->Window->Flags & ImGuiWindowFlags_ChildMenu) && ImGui::IsWindowChildOf(upper_popup->Window, window, true, false);
 }

 bool ImGui::BeginMenuEx(const char* label, const char* icon, bool enabled)
@@ -9101,8 +9112,10 @@ bool ImGui::MenuItem(const char* label, const char* shortcut, bool* p_selected,
 // - TabBarCalcMaxTabWidth() [Internal]
 // - TabBarFindTabById() [Internal]
 // - TabBarFindTabByOrder() [Internal]
+// - TabBarFindMostRecentlySelectedTabForActiveWindow() [Internal]
 // - TabBarGetCurrentTab() [Internal]
 // - TabBarGetTabName() [Internal]
+// - TabBarAddTab() [Internal]
 // - TabBarRemoveTab() [Internal]
 // - TabBarCloseTab() [Internal]
 // - TabBarScrollClamp() [Internal]
@@ -9224,7 +9237,8 @@ bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImG

    // Ensure correct ordering when toggling ImGuiTabBarFlags_Reorderable flag, or when a new tab was added while being not reorderable
    if ((flags & ImGuiTabBarFlags_Reorderable) != (tab_bar->Flags & ImGuiTabBarFlags_Reorderable) || (tab_bar->TabsAddedNew && !(flags & ImGuiTabBarFlags_Reorderable)))
-        ImQsort(tab_bar->Tabs.Data, tab_bar->Tabs.Size, sizeof(ImGuiTabItem), TabItemComparerByBeginOrder);
+        if ((flags & ImGuiTabBarFlags_DockNode) == 0) // FIXME: TabBar with DockNode can now be hybrid
+            ImQsort(tab_bar->Tabs.Data, tab_bar->Tabs.Size, sizeof(ImGuiTabItem), TabItemComparerByBeginOrder);
    tab_bar->TabsAddedNew = false;

    // Flags
@@ -9506,6 +9520,10 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
    tab_bar->VisibleTabId = tab_bar->SelectedTabId;
    tab_bar->VisibleTabWasSubmitted = false;

+    // CTRL+TAB can override visible tab temporarily
+    if (g.NavWindowingTarget != NULL && g.NavWindowingTarget->DockNode && g.NavWindowingTarget->DockNode->TabBar == tab_bar)
+        tab_bar->VisibleTabId = scroll_to_tab_id = g.NavWindowingTarget->TabId;
+
    // Apply request requests
    if (scroll_to_tab_id != 0)
        TabBarScrollToTab(tab_bar, scroll_to_tab_id, sections);
@@ -9551,11 +9569,11 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
 // Dockable windows uses Name/ID in the global namespace. Non-dockable items use the ID stack.
 static ImU32   ImGui::TabBarCalcTabID(ImGuiTabBar* tab_bar, const char* label, ImGuiWindow* docked_window)
 {
-    IM_ASSERT(docked_window == NULL); // master branch only
-    IM_UNUSED(docked_window);
-    if (tab_bar->Flags & ImGuiTabBarFlags_DockNode)
+    if (docked_window != NULL)
    {
-        ImGuiID id = ImHashStr(label);
+        IM_UNUSED(tab_bar);
+        IM_ASSERT(tab_bar->Flags & ImGuiTabBarFlags_DockNode);
+        ImGuiID id = docked_window->TabId;
        KeepAliveID(id);
        return id;
    }
@@ -9589,6 +9607,20 @@ ImGuiTabItem* ImGui::TabBarFindTabByOrder(ImGuiTabBar* tab_bar, int order)
    return &tab_bar->Tabs[order];
 }

+// FIXME: See references to #2304 in TODO.txt
+ImGuiTabItem* ImGui::TabBarFindMostRecentlySelectedTabForActiveWindow(ImGuiTabBar* tab_bar)
+{
+    ImGuiTabItem* most_recently_selected_tab = NULL;
+    for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
+    {
+        ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
+        if (most_recently_selected_tab == NULL || most_recently_selected_tab->LastFrameSelected < tab->LastFrameSelected)
+            if (tab->Window && tab->Window->WasActive)
+                most_recently_selected_tab = tab;
+    }
+    return most_recently_selected_tab;
+}
+
 ImGuiTabItem* ImGui::TabBarGetCurrentTab(ImGuiTabBar* tab_bar)
 {
    if (tab_bar->LastTabItemIdx < 0 || tab_bar->LastTabItemIdx >= tab_bar->Tabs.Size)
@@ -9598,12 +9630,35 @@ ImGuiTabItem* ImGui::TabBarGetCurrentTab(ImGuiTabBar* tab_bar)

 const char* ImGui::TabBarGetTabName(ImGuiTabBar* tab_bar, ImGuiTabItem* tab)
 {
+    if (tab->Window)
+        return tab->Window->Name;
    if (tab->NameOffset == -1)
        return "N/A";
    IM_ASSERT(tab->NameOffset < tab_bar->TabsNames.Buf.Size);
    return tab_bar->TabsNames.Buf.Data + tab->NameOffset;
 }

+// The purpose of this call is to register tab in advance so we can control their order at the time they appear.
+// Otherwise calling this is unnecessary as tabs are appending as needed by the BeginTabItem() function.
+void ImGui::TabBarAddTab(ImGuiTabBar* tab_bar, ImGuiTabItemFlags tab_flags, ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(TabBarFindTabByID(tab_bar, window->TabId) == NULL);
+    IM_ASSERT(g.CurrentTabBar != tab_bar);  // Can't work while the tab bar is active as our tab doesn't have an X offset yet, in theory we could/should test something like (tab_bar->CurrFrameVisible < g.FrameCount) but we'd need to solve why triggers the commented early-out assert in BeginTabBarEx() (probably dock node going from implicit to explicit in same frame)
+
+    if (!window->HasCloseButton)
+        tab_flags |= ImGuiTabItemFlags_NoCloseButton;       // Set _NoCloseButton immediately because it will be used for first-frame width calculation.
+
+    ImGuiTabItem new_tab;
+    new_tab.ID = window->TabId;
+    new_tab.Flags = tab_flags;
+    new_tab.LastFrameVisible = tab_bar->CurrFrameVisible;   // Required so BeginTabBar() doesn't ditch the tab
+    if (new_tab.LastFrameVisible == -1)
+        new_tab.LastFrameVisible = g.FrameCount - 1;
+    new_tab.Window = window;                                // Required so tab bar layout can compute the tab width before tab submission
+    tab_bar->Tabs.push_back(new_tab);
+}
+
 // The *TabId fields are already set by the docking system _before_ the actual TabItem was created, so we clear them regardless.
 void ImGui::TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id)
 {
@@ -9893,7 +9948,7 @@ bool    ImGui::BeginTabItem(const char* label, bool* p_open, ImGuiTabItemFlags f
        IM_ASSERT_USER_ERROR(tab_bar, "Needs to be called between BeginTabBar() and EndTabBar()!");
        return false;
    }
-    IM_ASSERT(!(flags & ImGuiTabItemFlags_Button)); // BeginTabItem() Can't be used with button flags, use TabItemButton() instead!
+    IM_ASSERT((flags & ImGuiTabItemFlags_Button) == 0);             // BeginTabItem() Can't be used with button flags, use TabItemButton() instead!

    bool ret = TabItemEx(tab_bar, label, p_open, flags, NULL);
    if (ret && !(flags & ImGuiTabItemFlags_NoPushId))
@@ -10003,11 +10058,14 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
    const bool is_tab_button = (flags & ImGuiTabItemFlags_Button) != 0;
    tab->LastFrameVisible = g.FrameCount;
    tab->Flags = flags;
+    tab->Window = docked_window;

    // Append name _WITH_ the zero-terminator
+    // (regular tabs are permitted in a DockNode tab bar, but window tabs not permitted in a non-DockNode tab bar)
    if (docked_window != NULL)
    {
-        IM_ASSERT(docked_window == NULL); // master branch only
+        IM_ASSERT(tab_bar->Flags & ImGuiTabBarFlags_DockNode);
+        tab->NameOffset = -1;
    }
    else
    {
@@ -10032,7 +10090,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
        tab_bar->VisibleTabWasSubmitted = true;

    // On the very first frame of a tab bar we let first tab contents be visible to minimize appearing glitches
-    if (!tab_contents_visible && tab_bar->SelectedTabId == 0 && tab_bar_appearing)
+    if (!tab_contents_visible && tab_bar->SelectedTabId == 0 && tab_bar_appearing && docked_window == NULL)
        if (tab_bar->Tabs.Size == 1 && !(tab_bar->Flags & ImGuiTabBarFlags_AutoSelectNewTabs))
            tab_contents_visible = true;

@@ -10080,30 +10138,82 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
    }

    // Click to Select a tab
-    // Allow the close button to overlap
    ImGuiButtonFlags button_flags = ((is_tab_button ? ImGuiButtonFlags_PressedOnClickRelease : ImGuiButtonFlags_PressedOnClick) | ImGuiButtonFlags_AllowOverlap);
-    if (g.DragDropActive)
+    if (g.DragDropActive && !g.DragDropPayload.IsDataType(IMGUI_PAYLOAD_TYPE_WINDOW)) // FIXME: May be an opt-in property of the payload to disable this
        button_flags |= ImGuiButtonFlags_PressedOnDragDropHold;
    bool hovered, held;
    bool pressed = ButtonBehavior(bb, id, &hovered, &held, button_flags);
    if (pressed && !is_tab_button)
        TabBarQueueFocus(tab_bar, tab);

-    // Drag and drop: re-order tabs
-    if (held && !tab_appearing && IsMouseDragging(0))
+    // Transfer active id window so the active id is not owned by the dock host (as StartMouseMovingWindow()
+    // will only do it on the drag). This allows FocusWindow() to be more conservative in how it clears active id.
+    if (held && docked_window && g.ActiveId == id && g.ActiveIdIsJustActivated)
+        g.ActiveIdWindow = docked_window;
+
+    // Drag and drop a single floating window node moves it
+    ImGuiDockNode* node = docked_window ? docked_window->DockNode : NULL;
+    const bool single_floating_window_node = node && node->IsFloatingNode() && (node->Windows.Size == 1);
+    if (held && single_floating_window_node && IsMouseDragging(0, 0.0f))
    {
-        if (!g.DragDropActive && (tab_bar->Flags & ImGuiTabBarFlags_Reorderable))
+        // Move
+        StartMouseMovingWindow(docked_window);
+    }
+    else if (held && !tab_appearing && IsMouseDragging(0))
+    {
+        // Drag and drop: re-order tabs
+        int drag_dir = 0;
+        float drag_distance_from_edge_x = 0.0f;
+        if (!g.DragDropActive && ((tab_bar->Flags & ImGuiTabBarFlags_Reorderable) || (docked_window != NULL)))
        {
            // While moving a tab it will jump on the other side of the mouse, so we also test for MouseDelta.x
            if (g.IO.MouseDelta.x < 0.0f && g.IO.MousePos.x < bb.Min.x)
            {
+                drag_dir = -1;
+                drag_distance_from_edge_x = bb.Min.x - g.IO.MousePos.x;
                TabBarQueueReorderFromMousePos(tab_bar, tab, g.IO.MousePos);
            }
            else if (g.IO.MouseDelta.x > 0.0f && g.IO.MousePos.x > bb.Max.x)
            {
+                drag_dir = +1;
+                drag_distance_from_edge_x = g.IO.MousePos.x - bb.Max.x;
                TabBarQueueReorderFromMousePos(tab_bar, tab, g.IO.MousePos);
            }
        }
+
+        // Extract a Dockable window out of it's tab bar
+        const bool can_undock = docked_window != NULL && !(docked_window->Flags & ImGuiWindowFlags_NoMove) && !(node->MergedFlags & ImGuiDockNodeFlags_NoUndocking);
+        if (can_undock)
+        {
+            // We use a variable threshold to distinguish dragging tabs within a tab bar and extracting them out of the tab bar
+            bool undocking_tab = (g.DragDropActive && g.DragDropPayload.SourceId == id);
+            if (!undocking_tab) //&& (!g.IO.ConfigDockingWithShift || g.IO.KeyShift)
+            {
+                float threshold_base = g.FontSize;
+                float threshold_x = (threshold_base * 2.2f);
+                float threshold_y = (threshold_base * 1.5f) + ImClamp((ImFabs(g.IO.MouseDragMaxDistanceAbs[0].x) - threshold_base * 2.0f) * 0.20f, 0.0f, threshold_base * 4.0f);
+                //GetForegroundDrawList()->AddRect(ImVec2(bb.Min.x - threshold_x, bb.Min.y - threshold_y), ImVec2(bb.Max.x + threshold_x, bb.Max.y + threshold_y), IM_COL32_WHITE); // [DEBUG]
+
+                float distance_from_edge_y = ImMax(bb.Min.y - g.IO.MousePos.y, g.IO.MousePos.y - bb.Max.y);
+                if (distance_from_edge_y >= threshold_y)
+                    undocking_tab = true;
+                if (drag_distance_from_edge_x > threshold_x)
+                    if ((drag_dir < 0 && TabBarGetTabOrder(tab_bar, tab) == 0) || (drag_dir > 0 && TabBarGetTabOrder(tab_bar, tab) == tab_bar->Tabs.Size - 1))
+                        undocking_tab = true;
+            }
+
+            if (undocking_tab)
+            {
+                // Undock
+                // FIXME: refactor to share more code with e.g. StartMouseMovingWindow
+                DockContextQueueUndockWindow(&g, docked_window);
+                g.MovingWindow = docked_window;
+                SetActiveID(g.MovingWindow->MoveId, g.MovingWindow);
+                g.ActiveIdClickOffset -= g.MovingWindow->Pos - bb.Min;
+                g.ActiveIdNoClearOnFocusLoss = true;
+                SetActiveIdUsingAllKeyboardKeys();
+            }
+        }
    }

 #if 0
@@ -10139,7 +10249,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
        flags |= ImGuiTabItemFlags_NoCloseWithMiddleMouseButton;

    // Render tab label, process close button
-    const ImGuiID close_button_id = p_open ? GetIDWithSeed("#CLOSE", NULL, id) : 0;
+    const ImGuiID close_button_id = p_open ? GetIDWithSeed("#CLOSE", NULL, docked_window ? docked_window->ID : id) : 0;
    bool just_closed;
    bool text_clipped;
    TabItemLabelAndCloseButton(display_draw_list, bb, tab_just_unsaved ? (flags & ~ImGuiTabItemFlags_UnsavedDocument) : flags, tab_bar->FramePadding, label, id, close_button_id, tab_contents_visible, &just_closed, &text_clipped);
@@ -10149,6 +10259,11 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
        TabBarCloseTab(tab_bar, tab);
    }

+    // Forward Hovered state so IsItemHovered() after Begin() can work (even though we are technically hovering our parent)
+    // That state is copied to window->DockTabItemStatusFlags by our caller.
+    if (docked_window && (hovered || g.HoveredId == close_button_id))
+        g.LastItemData.StatusFlags |= ImGuiItemStatusFlags_HoveredWindow;
+
    // Restore main window position so user can draw there
    if (want_clip_rect)
        PopClipRect();
@@ -10183,6 +10298,16 @@ void    ImGui::SetTabItemClosed(const char* label)
        if (ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, tab_id))
            tab->WantClose = true; // Will be processed by next call to TabBarLayout()
    }
+    else if (ImGuiWindow* window = FindWindowByName(label))
+    {
+        if (window->DockIsActive)
+            if (ImGuiDockNode* node = window->DockNode)
+            {
+                ImGuiID tab_id = TabBarCalcTabID(node->TabBar, label, window);
+                TabBarRemoveTab(node->TabBar, tab_id);
+                window->DockTabWantClose = true;
+            }
+    }
 }

 ImVec2 ImGui::TabItemCalcSize(const char* label, bool has_close_button_or_unsaved_marker)
@@ -10197,10 +10322,9 @@ ImVec2 ImGui::TabItemCalcSize(const char* label, bool has_close_button_or_unsave
    return ImVec2(ImMin(size.x, TabBarCalcMaxTabWidth()), size.y);
 }

-ImVec2 ImGui::TabItemCalcSize(ImGuiWindow*)
+ImVec2 ImGui::TabItemCalcSize(ImGuiWindow* window)
 {
-    IM_ASSERT(0); // This function exists to facilitate merge with 'docking' branch.
-    return ImVec2(0.0f, 0.0f);
+    return TabItemCalcSize(window->Name, window->HasCloseButton || (window->Flags & ImGuiWindowFlags_UnsavedDocument));
 }

 void ImGui::TabItemBackground(ImDrawList* draw_list, const ImRect& bb, ImGuiTabItemFlags flags, ImU32 col)
@@ -0,0 +1,92 @@
+Copyright (c) 2016 The Inter Project Authors (https://github.com/rsms/inter)
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+http://scripts.sil.org/OFL
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded,
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION AND CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.