At 06:12 AM 2/21/01, Alan Kay wrote:
>I think there is a contemporary one called Pad++ that one can find on 
>the Internet, and they may have references to goodies from the past 
>(though people these days are quite careless about acknowledging 
>prior art -- partly from ignorance and partly from who knows just 
>what?)

In defense of people these days, many early interfaces appear primarily as
video; the literature published about them is extremely sparse or even
non-existent.  While video is generally much better at communicating
interfaces, it can be extremely difficult to get your hands on a copy (or
even to discover that it exists).  We just need to convince the early
pioneers (like the Media Lab) to digitize all their old videos and put them
on the web.

The current incarnation of Pad++ is now called Jazz.  Ben Bederson is
working on it at the University of Maryland.  It's written in Java, open
source, and available free from http://www.cs.umd.edu/hcil/jazz.

References:

B. Bederson, L. Good, and J. Meyer. Jazz: An Extensible Zoomable User
Interface Graphics Toolkit in Java. Proceedings of UIST 2000.

B. Bederson and J. Hollan. Pad++: A Zoomable Graphical Interface for
Exploring Alternate Interface Physics. Proceedings of UIST 1994, pages 17-26.

K. Perlin and D. Fox. Pad: An Alternative Approach to the Computer
Interface. SIGGRAPH 1993, pages 57-72.

There are others, but those are the main three of the Pad -> Pad++ -> Jazz
progression.

Jeff