@mntmn From a previous message in the linked issue:
```
(lxappearance:25385): GLib-GObject-WARNING **: 16:59:24.185: invalid cast from 'GdkWaylandDisplay' to 'GdkX11Display'
```
I could be wrong but I really doubt that the pointer is indeed valid, to me it is just a pointer to a Wayland display passed as an X11 one. If it was indeed a bug in Xwayland , `GDK_BACKEND=x11 lxappearance` would not work either.