anchor.diff:    (stream-replay stream region))
   
   (defmethod handle-event ((stream output-recording-stream) (event window-repaint-event))
  -  (repaint-sheet stream nil))
  +  (repaint-sheet stream (window-event-region event)))
   
   (defmethod handle-event ((stream output-recording-stream) (event pointer-button-press-event))
     (with-slots (button x y) event
  
positive.code:   (let ((method-name (intern (format nil "MEDIUM-~A*" name)))
  	(class-name (intern (format nil "~A-OUTPUT-RECORD" name)))
  	(old-medium (gensym))
  	(new-medium (gensym)))
      `(progn
         (defclass ,class-name (graphics-displayed-output-record)
  	 ,(compute-class-vars args))
  
negative.code: 		      stream ink clipping-region transformation
  		      line-style text-style
  		      ,@args) graphic
             (let ((,border (1+ (/ (line-style-thickness line-style) 2))))
               (multiple-value-bind (lf tp rt bt) (progn ,@body)
                 (setq x1 (- lf ,border)
                       y1 (- tp ,border)
                       x2 (+ rt ,border)
                       y2 (+ bt ,border))))))
         (defmethod ,method-name :around ((stream output-recording-stream) ,@args)
  	 (with-sheet-medium (medium stream)
  	   (when (stream-recording-p stream)
  