Arrange In Front

If you have several documents or windows open in an app, and some are behind the windows of other apps, you can bring them all to the front by choosing Window, Bring All to Front. But if you hold down the Option key, then that menu item changes to Arrange in Front. This brings all the windows to the front, but also centers them, with each window being slightly to the right and down from the one behind it so you can see them all and select any one.