Very interesting.

Now HyperScope has been released, don't miss Brad Neuberg's great Screencast of Douglas Engelbart's Augment System

How much was SdiDesk influenced by Engelbart? Directly, not so much. But indirectly, obviously a lot. My direct influences were wiki, the Smalltalk environment, Emacs, HyperCard and the web-browser. Obviously, all, heavily indebted to Engelbart's work.