Flet's Linux picker asks the XDG desktop portal; window managers without one (IceWM, bare X11) answer
NameHasNoOwner and every pick raised. C.pick_files / C.pick_dir now fall back to zenity or kdialog (kdialog
first on KDE; core/pickers.py, run off the UI loop), and without either to a "type the full path" box. All
twelve pickers go through them.
