Drop events often don't trigger on Wayland

[s-fleuren]

When dropping a file from Nautilus to a tk window that is registered as a drop_target, the drop event often does not trigger when the mouse button is released. I can reproduce this with the following minimal example:

package require tkdnd

tkdnd::drop_target register . *
bind . <<Drop>> [list puts "drop ." ]
bind . <<DropEnter>> [list puts "dropEnter ."]

Then when repeatedly dragging the same file from Nautilus to the tk window, the DropEnter events always trigger but the Drop events only start triggering after a lot of tries:

<redacted>:$ TCLLIBPATH=<redacted>/tkdnd-2.9.5-linux-tcl8.6-i686/tkdnd2.9.5 wish testdnd.tcl 
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
dropEnter .
drop .
dropEnter .
drop .
dropEnter .
drop .

When I use an X11 session instead of Wayland everything works normally.

Tested on Ubuntu 24.04.4 LTS, GNOME 46.0

[tehrencron]

I could reproduce this issue and found that between xdnd::HandleXdndDrop in ./library/tkdnd_unix.tcl and generic::HandleDrop in ./library/tkdnd_generic.tcl a 'Leave' event is handled and processed which resets all relevant variables to {} at the end of generic::HandleLeave. Commenting this resetting makes it work, but this could have other consequences.