This is a brief one, and many of you will know about it already. If you use Apple Key + Shift + 4 to take screenshots, hold down the Space bar at the end of that combination. Your cursor will change from the crosshairs to a “camera” – which you can use to take a screenshot of an application window. And those screenshots will have a nice drop-shadow – something that the screenshot software I used to use (InstantShot!) does not include.
