When I hit F11 (while in fullscreen), to exit fullscreen, the maximize button on the top right of the window gets grayed out and is no longer usable until you restart minecraft.

What I expected to happen was...:
What should happen is it should return to its normal window without graying out the maximize button so I can use it normally after exiting fullscreen.

What actually happened was...:
The maximixe button was grayed out on several occasions because I exited fullscreen with the F11 key.

Steps to Reproduce:
1. Open minecraft 1.9.
2. Fullscreen in-game using F11.
3. Exit fullscreen using F11 and see the resulted grayed out maximize button.