Fix group update for valign/halign property change.
Fix group update for valign/halign property change.

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