anchor.diff:    (with-slots (armed) pane
       (when armed
         (setf armed t
  -	    (gadget-show-value-p pane) t
   	    (gadget-value pane :invoke-callback t) (convert-position-to-value pane (pointer-event-y event)))
         (dispatch-repaint pane (sheet-region pane)))))
   
  
positive.code: 		 :initarg :show-value-p
  		 :accessor gadget-show-value-p)))
  
  (defmethod drag-callback ((pane slider-pane) client gadget-id value)
    (declare (ignore client gadget-id))
    (when (slider-drag-callback pane)
  
negative.code: (defmethod handle-event ((pane slider-pane) (event pointer-enter-event))
    (with-slots (armed) pane
      (unless armed
        (setf armed t))
      (armed-callback pane (gadget-client pane) (gadget-id pane))))
  
  (defmethod handle-event ((pane slider-pane) (event pointer-exit-event))
    (with-slots (armed) pane
      (when armed
        (setf armed nil))
      (disarmed-callback pane (gadget-client pane) (gadget-id pane))))
  
  (defmethod handle-event ((pane slider-pane) (event pointer-button-press-event))
    (with-slots (armed) pane
       (when armed
         (setf armed ':button-press))))       
  
  (defmethod handle-event ((pane slider-pane) (event pointer-motion-event))
    (with-slots (armed) pane
  