Today I needed to crop a bunch of images in iPhoto to be used as wallpapers. At first I had to go “Edit”->”Crop”->”Constrain”->”(Display)”, then adjust the cropping area and click “done”, and move onto the next image and do these all over again. You don’t have to do this! I accidentally found out that after clicking “Crop” and selecting the desired constrain option, if you press left key or right key to move onto another image, the previous one will be automatically cropped and saved. This trick saved a lot of my time getting in and out of cropping mode.