File:Mouse tray.png

Summary
Screen shot taken from Douglas Engelbart's initial demonstration of mouse usage, showing an indented area of the workspace on the computer that is reserved for the mouse.

http://video.google.com/videoplay?docid=-8734787622017763097

Video (40 years old) has been released by original copyright holders onto Google video. While referred to as a source in Mousepad, the shot is fleeting and embedded. As such it is a screenshot of a demonstration of new technology, used for promotion.