Fix issue 111: fullscreen on linux.
Fix issue 111: fullscreen on linux.

seeminglee/pyglet64,seeminglee/pyglet64,adamlwgriffiths/Pyglet,adamlwgriffiths/Pyglet,seeminglee/pyglet64,niklaskorz/pyglet,niklaskorz/pyglet,niklaskorz/pyglet,adamlwgriffiths/Pyglet,niklaskorz/pyglet,adamlwgriffiths/Pyglet