A helpful window maneuver...

If you have a whole heap of windows and you want to move the back one without bringing it to the front there is a way to do this.  Just hold down the apple key and drag the back window, it will move but will not come to the front.  If you do the same except the option key not the apple key the front window(s) will hide while you move it, and you will need to show the apps to get all the other windows back...