Alt+Tabbing in fullscreen crashes the client

[MrYay]

Built from d93f05d for windows x86_64

Steps to reproduce:

1. Launch the client
2. Enable fullscreen
3. Try switching back to desktop (alt+tab)

Client crashes.

Doesn't happen in windowed mode.
Doesn't happen on the official build.

[travmon]

Tested build-115 windows x86_64 on 3 different machines, win7/nvidia, win7/intel graphics, win8.1/intel graphics. I had no issues with Alt+Tabbing. All opengl2, forgot to test with opengl1. Tried to run engine on athlon64 win7(outdated) with ati graphics, Could not get past Frozensand screen. I will not be updating that box. So if someone with AMD could test it would be helpful. "Alt-Tabbing" worked even though I could not get past Frozensand screen.