Would it be possible to add a no-border mode alongside windowed mode? I find it incredibly useful in case you have to alt+tab for whatever reason because you can get back in-game almost instantly. No-border was added to most Source games post Orange Box update and I just fell in love with it (activated by going into launch options and adding "-sw -noborder").
http://img40.imageshack.us/img40/175/windowednoborder.jpg
http://img40.imageshack.us/img40/175/windowednoborder.jpg