Actaully, when you hold "ALT", it captures the active window - E.G, if the active window [you know, this one's title bar is brigher and the other ones are slightly faded and greyed out] was an error, it would just copy the error.

However, this dosen't always work properley on all operating systems.

Originally Posted by TheArbiter

also another tip hole down Alt while pressing the Print Screen button and it removes the start bar from the screen shot Joe

Nice one Joe!