A cool trick for the Mac that can actually be useful at times... sometimes you want to move a window that does not have the focus, it's in the background. Normally you have to click on it, move it, then click back to where you were. But there is a shortcut that allows you to do this in one step. Just hold down the Command key. You can then click on the header of any background window and move it while it is in the background. It's pretty cool.