Slade is unusable under Wayland

[Blzut3]

SLADE Version: 3.2.2 Operating System: Linux

Issue Details: Under Wayland using the GTK3 version of wxWidgets 3.2.2.1 Slade is essentially unusable. The program will start but viewing lumps will result in the canvas covering the wrong area of the screen and generally unstable.

I'm mostly making this ticket to document the issue explicitly, since I'm guessing this is a wxWidgets issue and not much Slade can do about it at this time. (Although Slade could probably request the X11 GDK backend directly.)

Workaround in the mean time is to simply force Slade to run under XWayland. This can be accomplished by setting the GDK_BACKEND environment variable to x11.

GDK_BACKEND=x11 slade

For the DRD Team packages as of version 3.2.2-1 I've started making /usr/bin/slade a shell script which sets this. The flathub package at the time of this writing (3.2.1) does not forward Wayland and has been unaffected as a result.

Update 2023-10-12: Still unusable under wxWidgets 3.2.3 although there is a workaround. https://github.com/sirjuddington/SLADE/issues/1351#issuecomment-1759558662