Wayland: mouse grab constrains to incorrect rect

[vladislavbelov]

This issue isn't in SDL itself, but in mutter (https://gitlab.gnome.org/GNOME/mutter/-/issues/2740). I've created this issue in case someone will come across the same issue until the mutter's one is fixed. Feel free to close it if it's not needed.

We (0 A.D.) have met a bug (https://trac.wildfiregames.com/ticket/6649) on GNOME (mutter): after enabling mouse grab (SDL_SetWindowGrab(window, SDL_TRUE)) the mouse is restricted to an incorrect rect. It seems the confinement region is outdated after window creation/resize. After switching an active window back and forth (Alt - Tab) without any other action the region becomes valid until next resize.

I was able to reproduce it on Ubuntu 22.04, Ubuntu 22.10, Fedora 37 and Fedora 38 Beta with enabled Wayland SDL backend via SDL_VIDEODRIVER=wayland. It's reproducible even for a simple SDL sample after calling SDL_SetWindowGrab(window, SDL_TRUE) on a start.