When switching from windowed to fullscreen, the whole screen blacks out -- even if you switch to another window or workspace -- until Alt-Tab is used to get back to the game itself. Also, fullscreen mode generates this log message in the Marco WM (X11, default in MATE):

Window manager warning: Window 0x8200001 (Freedom Pl) sets an MWM hint indicating it isn't resizable, but sets min size 1 x 1 and max size 2147483647 x 2147483647; this doesn't make much sense.