Minecraft Window is a resizes

Upon clicking back into minecraft after pausing a video, it re-sizes back to whatever size the launcher is set to.

I expected it to remain the same size as it was before I clicked out

It re-sized itself back into the original width and height

1. Open minecraft
2. Login to 1.6.1
3. Make the screen a random size that isnt default, but not fullscreen
4. Create a world, any kind
5. Click out of the minecraft window after pressing escape
6. Click back in the minecraft window