Fullscreen: blocks become x-ray like.

While playing I pressed F1 to hide the HUD and then entered fullscreen with F11. After doing this all blocks became opaque(x-ray like).

What I expected to happen was...:
HUD hidden and fullscreen.

What actually happened was...:
HUD hidden, fullscreen, and all blocks became opaque.

.Steps to Reproduce:
1. In windowed mode hit F1 to hide HUD.
2. Hit F11 to go to fullscreen.
3. All blocks become opaque.
4. ???
5. Profit.