anchor.diff:    (let ((frame (make-application-frame 'sliderdemo)))
       (run-frame-top-level frame)))
   
  -(defmacro queue-number(int)
  +(defmacro queue-integer(int)
     `(lambda (gadget)
        (declare (ignore gadget))
        (let ((last-item (first (last *calc*))))
  
positive.code:             :space-requirement (make-space-requirement
                                  :width 50 :height 50)
              :label ,label
              :activate-callback (queue-operator #',operator)))
  
    (defun make-number-button-form (name label number)
      `(,name :push-button
              :space-requirement (make-space-requirement
                                  :width 50 :height 50)
              :label ,label
              :activate-callback (queue-number ,number))))
  
  (define-application-frame sliderdemo () ()
    (:panes #.(make-operator-button-form 'plus "+" '+)
  
negative.code:        (setf (gadget-value *text-field*)
               (princ-to-string (first (last *calc*)))))))
  
  (defmacro queue-op (operator)
    `(lambda (gadget)
       (declare (ignore gadget))
       (do-operation t)
  