Fullscreen Bug when the "fullscreen" window button is pressed.

Put the summary of the bug you're having here: There is a blue box above screen when fullscreen is triggered, But the Minecraft Fullscreen button works.

*What I expected to happen was: A fullscreen Game.

*What actually happened was: A blue box appeared above my game

Steps to Reproduce:
1. Open minecraft to 1.8.3 (not maximized)
2. once IN A WORLD press the little green button to maximize the screen to full(sometimes you need to press the minecraft fullscreen button on and off then press the green button)
3 Next Look at the box above your screen 😛 (Its blue for me)