Remove Shadows from Mac OS X with ShadowKiller
Ever wanted to remove shadows from windows, menus, and box items in Mac OS X? You can with a free tool called ShadowKiller, and it works in newish versions of OS X too. All you need to do is launch the app, the screen will flicker briefly, and all on screen windows will appear shadowless. You can get the shadows back by just relaunching the app again. If you want to have the window shadows always disabled, you’ll need to throw ShadowKiller into Login Items.
Why would you want to do this? At this point it’s probably a matter of preference, but Shadowkiller was created to speed up performance of Mac OS X on older and slower hardware, and it reportedly works fairly well for that purpose. Frankly, leaving window and box shadows enabled looks much better, so unless you have a compelling reason to do so, you’ll probably want to keep them around.
Remember this disables the window and menu shadows all the time, not exclusively in screen captures. For the latter, you can disable the shadow in screenshots only with a defaults write command or by using Grab or the Terminal to take a one-off screenshot minus the 3D look.
Nice little find by Jeff Bearnam, who reminds us that yes the app works despite Unsanity’s warning that it isn’t compatible with newer versions of OS X.