anchor.diff:  (defclass menu-button (value-gadget labelled-gadget-mixin) ()
     (:documentation "The value is a button"))
   
  -(defclass menu-button-pane (menu-button clim-stream-pane) ())
  +(defclass menu-button-pane (menu-button) ())
   
   (defclass clx-menu-button-pane (menu-button-pane) ())
   
  
positive.code: (defclass toggle-button (value-gadget labelled-gadget-mixin) ()
    (:documentation "The value is either t either nil"))
  
  (defclass toggle-button-pane (toggle-button clim-stream-pane)
    ((indicator-type :type (member '(:one-of :some-of))
  		   :initarg :indicator-type
  		   :reader toggle-button-indicator-type)))
  
negative.code: (defclass text-field (value-gadget action-gadget) ()
    (:documentation "The value is a string"))
  
  (defclass text-field-pane (text-field) ())
  
  (defmethod handle-event ((pane text-field-pane) (event window-repaint-event))
    (dispatch-repaint pane (sheet-region pane)))
  
  (defmethod repaint-sheet ((pane text-field-pane) region)
    (declare (ignore region))
    (multiple-value-bind (x1 y1 x2 y2) (bounding-rectangle* (sheet-region pane))
      (draw-text* pane (gadget-value pane)
  		(round (- x2 x1))
  		(round (- y2 y1) 2)
  		:align-x :right
  		:align-y :center)))
  
  (defmethod (setf gadget-value) :after (value (pane text-field-pane) &key invoke-callback)
    (declare (ignore value invoke-callback))
    (window-clear pane)
    (dispatch-repaint pane (sheet-region pane)))
  
  (defclass clx-text-field-pane (text-field-pane) ())
  
  