We all know that by using Shift Command 3 we can take the capture the whole screen and using Shift Command 4 we can select the region to be screen captured.

Capturing Screen Window

There is a hidden trick behind screen capture, if you're pressing Shift Command 4+Spacebar, you will be able to capture a window hovered by your mouse along with the shadow.

You can also capture your menu bar, Dock and even additional menu extras of your Mac. I think you should try it. It's fun.

Disabling Shadow

If you don't like the shadow being captured, you can Disable shadow in screen window captures [MacOSXHints.com] with a simple command line.

Here is the command line defaults write com.apple.screencapture disable-shadow -bool true && killall SystemUIServer to prevent the shadow being screen captured.

And to restore back to original setting, you can use defaults delete com.apple.screencapture disable-shadow && killall SystemUIServer.

Have fun capturing your screen!