object-oriented Lisp user interfaces

[oravax!dean@cu-arpa.cs.cornell.edu (William Dean)]

Does anyone know of any good user interface
development tools or environments written in Lisp,
preferably Common Lisp or CLOS?

We are trying to select some software on which to develop portable
user interfaces for multiple workstations (Symbolics, Suns).

We're especially interested in flexible, extensible tools written
with object-oriented programming in mind.
Something like X-Windows, with client objects (not necessarily windows)
responding to messages from servers.

Thanks,

Bill