Anil Roychoudhry has just written a great writeup on how the Seamless feature began.
Anil was one of the original Datapac developers and is now a manager within the Sydney site for Citrix.
I highly recommend this article to find out how Seamless was created.
Hmmm. the link doesn’t appear to exist.
The domain citrite.org went away quite a few years ago. Unfortunately this information is most likely lost now.