Hi, I'm getting the following error reported when trying to setup a command to be executed when a scale widget is changed: wrong # args: should be "callback s" wrong # args: should be "callback s" while executing "callback w4 0" (command executed by scale) The following code reproduces this error. (defun command-test() (ltk:with-ltk () (let* ((f (make-instance 'ltk:frame)) (b1 (make-instance 'ltk:button :master f :text "Button 1" :command (lambda () (format t "Button~&")))) (scale (make-instance 'ltk:scale :master f :command (lambda (val) (format t "Scale val:~D~&" val))))) (ltk:pack f) (ltk:pack b1 :side :left) (ltk:pack scale :side :left) ))) I'm using LTK 0.91. Perhaps this is caused by a bug in the command sent to tk to set up a callback. Any pointers to the part of the code I should look at to fix this problem would be appreciated. Cheers, Russell