cannot supply target warnings

Using capi (under LWL fwiw), I'm getting a continuous stream of warnings:

  warning: cannot supply target :COMPOUND-TEXT.

Any idea what is causing this?  After I did some more work, the warnings 
stopped.

I was debugging some graphics and using (format t ...)'s.  When I finally got 
the i/o redirections correct this message started to appear (at one-second 
intervals) in the listener.  

It could be that something else I've done is causing this warning, but I 
wasn't seeing it because *standard-output* was not set to anything useful, 
or, it could be that my way of redirecting *standard-output* is broken.

[In fact, is there a better way to assign *standard-output* so that (format t 
...) can be used to debug capi / gp drawings?]

The way I redirect *standard-output* is to store the listener's original 
*standard-output* in a capi:object-property of a newly-created interface, 
then suck it back out on every input gesture and assign it to 
cl-user::*standard-output*, effectively:

        (let ((win (make-instance 'test-interface)))
          (setf (capi:capi-object-property (drawing-surface win) ':vf-stdout)
               cl-user::*standard-output*)
          (capi:display win)
...
(defun move-with-button-down-callback (drawing-surface-port x y)
   (setf *standard-output* (capi:capi-object-property drawing-surface-port 
':vf-stdout)
   ...


thanx
pt