anchor.diff:  			 top (min top t1 b1)
   			 right (max right l1 r1)
   			 bottom (max bottom t1 b1))))
  -	(setq x-min left
  -	      y-min top
  -	      x-max right
  -	      y-max bottom)))
  +	(setq x1 left
  +	      y1 top
  +	      x2 right
  +	      y2 bottom)))
       (if parent
  -	(recompute-extent-for-changed-child parent record x-min y-min x-max y-max))))
  +	(recompute-extent-for-changed-child parent record x1 y1 x2 y2))))
   
   (defclass standard-sequence-output-record (displayed-output-record)
     (
  
positive.code:     (setq children (delete child children))))
  
  (defmethod clear-output-record ((record output-record))
    (with-slots (children x-min y-min x-max y-max) record
      (setq children nil
  	  x-min 0
  	  y-min 0
  	  x-max 0
  	  y-max 0)))
  
  (defmethod output-record-count ((record output-record))
    (length (output-record-children record)))
  
negative.code: 	 ,(compute-class-vars args))
         (defmethod initialize-instance :after ((graphic ,class-name) &rest args)
  	 (declare (ignore args))
  	 (with-slots (x1 y1 x2 y2
  		      stream ink clipping-region transformation
  		      line-style text-style
  		      ,@args) graphic
  	   (multiple-value-bind (lf tp rt bt) (progn ,@body)
  	     (setq x1 lf
  		   y1 tp
  		   x2 rt
  		   y2 bt))))
         (defmethod ,method-name :around ((stream stream-output-history-mixin) ,@args)
  	 (with-sheet-medium (medium stream)
  	   (let ((record (make-instance ',class-name
  