Minecraft is getting a gray tint.

Put the summary of the bug you're having here:
When I'm playing my minecraft game, I occasionally have to exit out to do something. I press the windows button to go to the start menu, and then use the desktop task bar to get back. Usually after doing so, minecraft gets a annoying gray tint that lowers the shade of things. For example, green grass turns into grayish-green grass.

What I expected to happen was...:
Describe what you thought should happen here:
What I expected to happen was minecraft returning to it's normal self, and not experiencing any lighting issues.

What actually happened was...:
Describe what happened here:
Minecraft got a gray tint that makes the game look dull and annoying.

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...:
1. Go onto a minecraft world in windows 8
2. Exit out of the game by pressing the start button
3. Resume the game from the taskbar and look at the color shade.