Worked at Xerox PARC in the Systems Concepts Lab (The Smalltalk group) and later at SunLabs? in the Self group. Co-invented SelfLanguage with DavidUngar, and was the principal inventor and developer of the AlternateRealityKit, which had a DirectManipulation interface with DragAndDrop. AlternateRealityKit's unifying principle was that all objects in the system should be manifest on the screen, and directly manipulable by the user.
Currently at SunLabs?: http://research.sun.com/people/randy/