anchor.diff:    (with-slots (presentation) self
       (when presentation
         (erase-graphics-presentation presentation :stream STREAM)
  -      (setq presentation nil)
  -      #+clim-0.9 (clim-update-sensitivity stream))))
  +      (setq presentation nil))))
   
   (defmethod kill ((self basic-annotation) STREAM)
     "Erase the annotation and resign from the graph."
  
positive.code:       )))
  
  (defgeneric rescale-annotation (SELF)
    (:method-combination progn #-Lucid :most-specific-last)
    (:documentation "Called when the graph has been rescaled."))
  
  (defmethod rescale-annotation progn ((self t)) nil)
  
negative.code: (defmethod annotation-p ((annotation basic-annotation)) t)
  
  (defmethod editable ((object t)) nil)
  
  (defmethod annotation-presentation-type ((self basic-annotation)) 'annotation)
  (defmethod annotation-single-box ((self basic-annotation)) nil)
  