How to uncapture the mouse, like 90% of steam games?

[MrRandyKnight]

In almost every steam game I own I can set the game to windowed mode and move my mouse freely from the game to another window (email, web browsing, skype etc). I've tried every trick I could find online and only 1 marginally worked. It would allow you to move the mouse outside of the window but the mouse outside of the game was invisible. When you brought the mouse back into the game it was horribly synced. I know in Virtual PC there is a checkbox you click and it will allow you to capture and uncapture the mouse. I'm hoping its just a matter of adding a couple lines to the .ini file to fix thing. Thanks