anchor.diff:  	  (:presentation (&key presentation window event x y)
   	    (let ((dest-translator (find-dest-translator presentation window
   							 x y)))
  -	      (do-feedback (last-window) (last-x) (last-y)
  -			   :unhighlight feedback-activated)
  +	      (when feedback-activated
  +		(do-feedback (last-window) (last-x) (last-y) :unhighlight))
   	      (setq feedback-activated t
   		    last-event event)
  -	      (do-hilite last-presentation (last-window) :unhighlight)
  +	      (when last-presentation
  +		(do-hilite last-presentation (last-window) :unhighlight))
   	      (setq last-presentation presentation
   		    feedback-fn (feedback dest-translator)
   		    hilite-fn (highlighting dest-translator))
   	      (do-hilite presentation window :highlight)
  -	      (do-feedback window x y :highlight t)
  +	      (do-feedback window x y :highlight)
   	      (document-drag-n-drop dest-translator presentation
   				    context-type frame event window
   				    x y)))
   	  (:pointer-motion (&key event window x y)
  -	    (do-feedback (last-window) (last-x) (last-y)
  -			 :unhighlight feedback-activated)
  +	    (when feedback-activated
  +	      (do-feedback (last-window) (last-x) (last-y) :unhighlight))
   	    (setq feedback-activated t
   		  last-event event)
  -	    (do-hilite last-presentation (last-window) :unhighlight)
  +	    (when last-presentation
  +	      (do-hilite last-presentation (last-window) :unhighlight))
   	    (setq last-presentation nil)
  -	    (do-feedback window x y :highlight t)
  +	    (do-feedback window x y :highlight)
   	    (document-drag-n-drop translator nil
   				  context-type frame event window
   				  x y))
  
positive.code: 							   window x y))
  		   do (return-from find-dest-translator translator))
  	     nil)
  	   (do-feedback (window x y state do-it)
  	     (when do-it
  	       (funcall feedback-fn frame from-presentation window
  			initial-x initial-y x y state)))
  	   (do-hilite (presentation window state)
  	     (when presentation
  	       (funcall hilite-fn frame presentation window state)))
  	   (last-window ()
  	     (event-sheet last-event))
  	   (last-x ()
  
negative.code:       (window-clear s)
        (with-end-of-page-action (s :allow)
  	(with-end-of-line-action (s :allow)
  	  (funcall (pointer-documentation translator)
  	   *dragged-object*
  	   :presentation *dragged-presentation*
  	   :destination-object (and presentation
  				    (presentation-object presentation))
  	   :destination-presentation presentation
  	   :context-type context-type
  	   :frame frame
  	   :event event
  	   :window window
  	   :x x
  	   :y y
  	   :stream s))))))
  
  
  
  