Sketchpad - almost 50 years old and still revolutionary

I came across this video on Google+ of Alan Kay presenting Ivan Sutherland's Sketchpad (aka the Robot Draftsman). This was a revolutionary program written by Ivan Sutherland in 1963 for his PhD thesis that changed the way people interacted with computers. Sketchpad is  the ancestor of modern computer-aided drafting (CAD). The Graphical User Interface (GUI) was derived from Sketchpad (it was the first program to use a "window") as well as object oriented programming. Ivan Sutherland demonstrated with Sketchpad that computer graphics could be used for artistic and technical purposes in addition to showing a new method of human-computer interaction. Sutherland received the Turing Award (computing's highest honour) in 1988. 

 This video is an excerpt of a longer one here.  Sutherland's Ph.D. thesis from MIT was reprinted in 1980 as Sketchpad: A Man-Machine Graphical Communication System.