When you open minecraft it goes in full screen, when you press F11 to go out of it and try and go in windowed full screen it wont let you
Link: https://youtu.be/9de7vaaLqNk?t=2m11s
(Or I made a full video on bugs and glitches if you want to watch it all)
Also I heard you would get a cape from this?

• Thanks ~ Pydro