Express Windows

["William D. Gooch" <ai.gooch@MCC.COM>]

    Liszt Programming has come out with a product called "Express Windows", 
    that they claim is "the most powerful window toolkit for Common Lisp and X."
    It runs on standard platforms and provides user interface features like the
    ones on the Symbolics machines.  The pitch seems to be that your programs can
    fully exploit the user-interface features found on your Lisp Machine (where
    you would rather do development) without worrying about portability.

    Express Windows is a Common Lisp package that you run on your delivery machine
    to endow it with presentation-types, accepting-values menus, and other
    user-interface wonderfulness.  They say that all the usual forms like
    DEFINE-PRESENTATION-TYPE are available.  I asked one of the Liszt programmers
    if it was really source compatible with Genera, and he said, "The only thing
    we didn't get around to was MAP-OVER-SUBTYPES", but that everything else was
    there.

Does anyone have input as to the possible implications of this?