anchor.diff:          (make-array length :displaced-to arr :displaced-index-offset (- orig-len length)))))
   
   (defun display-main (frame stream)
  -  (declare (ignore frame))
  -  (when (= 0 (length (val-array *application-frame*)))
  +  (when (= 0 (length (val-array frame)))
       (return-from display-main nil))
     (let* ((left-x-padding 30)
  -         (pane (find-pane-named *application-frame* 'main-display))
  -         (values (sub-array-for (val-array *application-frame*) (max-xvals *application-frame*)))
  +         (pane (find-pane-named frame 'main-display))
  +         (values (sub-array-for (val-array frame)
  +                                (max-xvals frame)))
            (maximum (if (> (length values) 0) (reduce #'max values) 0))
            (minimum (if (> (length values) 0) (reduce #'min values) 0))
            (variance (- maximum minimum))
  
positive.code:                       (+ (- height (truncate (* h-step (+ y (- minimum))))) 50))))
  
      ;; Draw the title
      (draw-text* pane (format nil "~a" (title *application-frame*))
                  (/ width 2) 10)
      
      ;; Draw the Y labels
  
negative.code:     (example-data frame)))
  
  (defmethod handle-event ((frame graph-toy) (event refresh-event))
    (with-application-frame (frame)
     (redisplay-frame-pane frame 'main-display)))
  
  (defun add-value (graph val)
    (schedule-event (frame-top-level-sheet graph)
  