Fix issue 73: OS X mouse visibility.
Fix issue 73: OS X mouse visibility.

oktayacikalin/pyglet,theblacklion/pyglet,theblacklion/pyglet,mammadori/pyglet,oktayacikalin/pyglet,oktayacikalin/pyglet,mammadori/pyglet,mammadori/pyglet,theblacklion/pyglet,mammadori/pyglet,oktayacikalin/pyglet,theblacklion/pyglet,oktayacikalin/pyglet,theblacklion/pyglet