I think it's a bug. But I can't seem to find any information about it. The mouse pointer hides itself, but it is still possible to use it.
Whenever I start watching a video in VLC, or start playing KSP through Steam my mouse pointer disappears. But it's not returned upon exiting the application. I have not tried with other games in Steam. The mouse pointer does not disappear when watching videos online through YouTube at first, but it properly hides itself after a few seconds.
The bug came about after I updated to 13.10, it was not present with the same setup in 13.04. I've tried removing ~/.compiz and restarting the kernel module psmouse.
Going to tty1 and back to the desktop reveals the pointer, though this fix is bothering me.
How do I fix this problem?