I occasionally will pause a game (Running in full screen mode) and alt-tab out to read email, or look up a web page, or whatever. I've noticed that when I do this, if I use the scroll wheel on the mouse to navigate in my web browser, when I alt-tab back into the game, the zoom level will have changed. For example, I zoom all the way in, alt-tab out of the game to a web site, and scroll all the way to the bottom of a long page, then the game will be zoomed out when I reenter the game. Not really a bug with a huge impact, but reporting it anyway.