anchor.diff:  (defun gadgetp (object)
     (typep object 'gadget))
   
  +(defmethod compose-space ((gadget gadget))
  +  (pane-space-requirement gadget))
  +
   ;;
   ;; gadget's colors
   ;;
  
positive.code: (defclass menu-button (value-gadget labelled-gadget-mixin) ()
    (:documentation "The value is a button"))
  
  (defclass menu-button-pane (menu-button clim-stream-pane) ())
  
  (defclass clx-menu-button-pane (menu-button-pane) ())
  
  
negative.code: 	    x1 1
  	    y2 (- y2 y1 1)
  	    y1 1)
        (display-gadget-background pane x1 y1 x2 y2)
        (if (push-button-show-as-default-p pane)
  	  (draw-edges-lines* pane x2 y2 x1 y1)
  	  (draw-edges-lines* pane x1 y1 x2 y2))
        (draw-text* pane text
  		  (round (- x2 x1) 2)
  		  (round (- y2 y1) 2)
  