anchor.diff:  ;; in gadget-armed-callback or gadget-disarmed-callback with one argument,
   ;; the gadget."
   
  -(defmethod armed-callback ((gadget standard-gadget) client gadget-id)
  +(defmethod armed-callback ((gadget basic-gadget) client gadget-id)
     (declare (ignore client gadget-id))
     (invoke-callback gadget (gadget-armed-callback gadget)))
   
  -(defmethod disarmed-callback ((gadget standard-gadget) client gadget-id)
  +(defmethod disarmed-callback ((gadget basic-gadget) client gadget-id)
     (declare (ignore client gadget-id))
     (invoke-callback gadget (gadget-disarmed-callback gadget)))
   
  
positive.code: 
  ;;; Scroll-bar's sub-regions
  
  #+NIL
  (defmethod scroll-bar-thumb-size ((sb scroll-bar-pane))
    "Return the size of the scrollbar's thumb."
    (multiple-value-bind (minv maxv) (gadget-range* sb)
      (max 1/100000                         ;hack to cope with GADGET-RANGE* being empty
           (* 1/3 (- maxv minv)))))
  
  (defmethod (setf scroll-bar-thumb-size) :after (new-value (sb scroll-bar-pane))
    (declare (ignore new-value))
    (handle-repaint sb +everywhere+))     ;arg
  
  (defmethod scroll-bar-up-region ((sb scroll-bar-pane))
    (with-bounding-rectangle* (minx miny maxx maxy) (transform-region (scroll-bar-transformation sb)
  
negative.code:                        :min-height (* 2 *3d-border-thickness*)
                         :height (* 2 *3d-border-thickness*)
                         :max-height (* 2 *3d-border-thickness*)))
  
  ;;; ------------------------------------------------------------------------------------------
  ;;;  30.4.4 The concrete scroll-bar Gadget
  
  (defclass scroll-bar-pane (sheet-multiple-child-mixin
                             3D-border-mixin
                             scroll-bar
                             )
    ((event-state :initform nil)
     (drag-dy :initform nil)
     (inhibit-redraw-p
      :initform nil
      :documentation "Hack, when set to non-NIL changing something does not trigger redrawing.")
     (thumb :initform nil)
     )
    (:default-initargs :value 0
                       :min-value 0
                       :max-value 1
                       :orientation :vertical
                       :border-width 2
                       :border-style :inset
                       :background *3d-inner-color*))
  
  (defmethod compose-space ((sb scroll-bar-pane) &key width height)
    (declare (ignore width height))
  