First of all, this is awesome. Great idea, can't believe it hasn't been around till now, and will definitely be using it.

The only thing I could change here is the "x" icon when expanded. Someone mentioned here that they would be unnerved hitting an "x" button with a lot of text - this is definitely valid, I felt the same thing when trying it out. A simple change to an "exit full screen" icon (like this http://findicons.com/files/icons/1667/iconic/32/fullscreen_e...), would solve the problem nicely : )