anchor.diff:  
   (defmethod allocate-space ((pane spacing-pane) width height)
     (with-slots (border-width) pane
  -    (let ((child (first (sheet-children pane))))
  +    (let ((child (first (sheet-children pane)))
  +	  (new-width  (- width border-width border-width))
  +	  (new-height (- height border-width border-width)))
         (layout-child child (pane-align-x pane) (pane-align-y pane)
                       border-width border-width
  -                    (- width border-width border-width)
  -                    (- height border-width border-width)))))
  +		    new-width new-height))))
   
   ;;; OUTLINED PANE
   
  
positive.code: ; timer-event convenience
  
  (defmethod schedule-timer-event ((pane pane) token delay)
    (schedule-event pane (make-instance 'timer-event :token token :sheet pane) delay))
  
  
negative.code:   (:documentation "Returns the number of pixels respresenting a 'line', used
  to computed distance to scroll in response to mouse wheel events."))
  
  (defmethod scroll-quantum (pane) 10)	; TODO: Connect this with the scroller-pane motion
  
  (defun find-viewport-for-scroll (pane)
    "Find a viewport in the chain of parents which contains 'pane',
     returning this viewport and the sheet immediately contained within."
    (cond ((not (typep pane 'basic-pane))
           (values nil nil))
  	((pane-viewport pane) (values (pane-viewport pane) pane))
  	(t (find-viewport-for-scroll (sheet-parent pane)))))
  
  (defun scroll-sheet (sheet vertical horizontal)
    (multiple-value-bind (viewport sheet)
        (find-viewport-for-scroll sheet)
      (declare (ignore viewport))
      (with-bounding-rectangle* (vx0 vy0 vx1 vy1) (pane-viewport-region sheet)
        (with-bounding-rectangle* (sx0 sy0 sx1 sy1) (sheet-region sheet)
  	(let ((viewport-height (- vy1 vy0))
  	      (viewport-width  (- vx1 vx0))
  	      (delta (* *mouse-scroll-distance*
  			(scroll-quantum sheet))))
  	  ;; The coordinates (x,y) of the new upper-left corner of the viewport
  	  ;; must be "sx0 < x < sx1 - viewport-width"  and
  	  ;;         "sy0 < y < sy1 - viewport-height"
  	  (scroll-extent sheet
  			 (max sx0 (min (- sx1 viewport-width)  (+ vx0 (* delta horizontal))))
  			 (max sy0 (min (- sy1 viewport-height) (+ vy0 (* delta vertical))))))))))
  
  ;; Note that handling this from dispatch-event is evil, and we shouldn't.
  (defmethod dispatch-event :around ((sheet mouse-wheel-scroll-mixin)
                                     (event pointer-button-press-event))
    (if (find-viewport-for-scroll sheet)
        (let ((button (pointer-event-button event)))
  	(cond
  	 ((eq button +pointer-wheel-up+)    (scroll-sheet sheet -1  0))
  