Maximizing screen while loading a world doesn't work in 1.6.1.

Put the summary of the bug you're having here

What I expected to happen was...:
Maximizing the screen.

What actually happened was...:
The Minecraft screen didn't maximize.

Steps to Reproduce:
1. Login to Minecraft and minimize your Minecraft.
2. Load or create a world.
3. Maximize your screen while your world is loading.