anchor.diff:                  (not (null (gadget-value c))))
         (setf (gadget-value c :invoke-callback invoke-callback) (eq c button)) )))
   
  +
  +(defmethod deactivate-gadget :after ((box radio-box-pane))
  +  (dolist (c (sheet-children box))
  +    (deactivate-gadget c))
  +  (dispatch-repaint box +everywhere+))
  +
  +(defmethod activate-gadget :after ((box radio-box-pane))
  +  (dolist (c (sheet-children box))
  +    (activate-gadget c))
  +  (dispatch-repaint box +everywhere+))
  +
  +
   ;; check-box
   
   (defclass check-box-pane (check-box rack-layout-mixin sheet-multiple-child-mixin basic-pane)
  
positive.code:    :background *3d-normal-color*))
  
  (defmethod initialize-instance :after ((pane radio-box-pane)
                                         &key choices current-selection orientation &allow-other-keys)
    (setf (box-layout-orientation pane) orientation)
    (setf (gadget-value pane) current-selection)
    (let ((children
  
negative.code:                      (setf (gadget-client c) pane)
                       c))
                   choices)))
      (mapc (curry #'sheet-adopt-child pane) children))
    (unless active
      (deactivate-gadget pane)))
  
  (defmethod deactivate-gadget :after ((box check-box-pane))
    (dolist (c (sheet-children box))
      (deactivate-gadget c))
    (dispatch-repaint box +everywhere+))
  
  (defmethod activate-gadget :after ((box check-box-pane))
    (dolist (c (sheet-children box))
      (activate-gadget c))
    (dispatch-repaint box +everywhere+))
  
  ;;; ------------------------------------------------------------------------------------------
  ;;;  30.4.7 The concrete list-pane and option-pane Gadgets
  