Tom,

> There have been a few GUIs built around the idea of using lots of
> lightweight processes, active objects, or actors.  
> (Incidentally, the best way for them to communicate seems
> to be via mailboxes asynchronous method calls, message passing,
> or pipes, not by calling each other's methods.)
> Such GUIs tend to be responsive and easier to program in my 
> experience.

Do you have some pointers to any of these?!

  - Andreas