Attached is the current LTK Lisp/Tk gui from Peter Herth:

http://www.peter-herth.de/ltk/

and modified as follows to work with GCL via the run-program function:

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$ diff  ltk.lisp{.bak,}
403a404,405

>     #+:gcl(si:run-program program args :input :stream :output :stream
> :error :output)

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(load (compile-file "ltk.lisp")) fails due to:

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;;; The constant NIL is being bound.
No matching method for the generic-function #<compiled-closure PCL::OBJECT-PLIST

>,

when called with arguments (MAKE-LTK-CONNECTION).

Fast links are on: do (si::use-fast-links nil) for debugging
Broken at NO-APPLICABLE-METHOD.  Type :H for Help.
 1 (Continue) Retry call to #<compiled-closure PCL::OBJECT-PLIST>
 2 (SYSTEM:ERROR-SET
       '(EVAL '(LET* ((#:G1903 'MAKE-LTK-CONNECTION)
                      (#:G1904 'FUNCTION)
                      (#:G1905 "Create a new LTK-CONNECTION object.  This repres
ents a connection to a
    specific wish.  You can maintain connections to several distinct wish
    processes by binding WISH to the one you desire to communicate with, and
    using LTK functions within that dynamic scope."))
                 (FUNCALL #'(SETF DOCUMENTATION) #:G1905 #:G1903
                          #:G1904))))
 3 Retry compiling file "ltk.lisp".
 4 Return to top level.
dbl:LTK>>
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Commenting out this line leads to further problems with the compiler.

I think that we should support LTK in GCL 2.7.0 as a quick third party cross platform GUI candidate usable by applications such as Axiom.

The previous stable version of LTK worked OK with HEAD with the above modification.