When I am running a fullscreen application, for example the game SPAZ from the HumbleBundle 6, if some popup comes or if I press the super key to come back to desktop and minimize the game, I am unable to play the game again. The game just wont lock my mouse again, I am sometimes able to get it to become fullscreen again (no idea exactly how!), but the mouse just wont get locked.. Any idea how to continue the game without exit and restart?
Try disabling mouse capture on the option menu that comes up when you start the game. Then you can wiggle the mouse when you get kicked out and it will re-focus on the game. Worked twice for me when I was playing last night. This also fixes the double mouse icon I was getting.
Still not sure why it looses focus on the full screen, that seems like a bug but I am not sure if it is with SPAZ or Ubuntu.