Can't play in Fullscreen

[Som1Lse]

You shouldn't have to download a program to run the game in fullscreen. If it works use it, but I'd rather figure out why the game fullscreen doesn't work.

Sure, but I actually prefer to use this program as it doesn't lock the mouse on the screen.
Imagine opening the game twice by mistake. (don't do it, you will lock the mouse at the top left corner of the screen without any chance to quit)