anchor.diff:    (window-clear pane)
     (dispatch-repaint pane (sheet-region pane)))
   
  +(defmethod compose-space ((pane text-field-pane))
  +  (with-sheet-medium (medium pane)
  +    (multiple-value-bind (width height)
  +	(text-size medium (gadget-value pane))
  +      (make-space-requirement :width width :height height
  +			      :max-width width :max-height height
  +			      :min-width width :min-height height))))
  +
   ;;
   ;; TEXT-EDITOR gadget
   ;;
  
positive.code: ;; MENU-BUTTON gadget
  ;;
  
  (defclass menu-button (value-gadget labelled-gadget-mixin)
    ()
    (:documentation "The value is a button"))
  
  
negative.code: (defun gadgetp (object)
    (typep object 'gadget))
  
  ;;
  ;; gadget's colors
  ;;
  