Ok, I tried the Libreoot update, unfortunately nothing improved (plus I have
to figure out what to modify in the grub.cfg for automatic boot, but that's
another story).
The only thing that kind of works is running the game with --render sdl.
The only issue is that since it's from the command line, it always opens in a
second window that remains at half the screen size. Bottom line : I need to
start the game with that option, and at full screen from the start.
Also I suppose I should ask the devs of the project.
