anchor.diff:  
   (defmethod erase-output-record (record (stream standard-output-recording-stream)
                                   &optional (errorp t))
  -  (letf (((stream-recording-p stream)  nil))
  +  (with-output-recording-options (stream :record nil)
       (let ((region (rounded-bounding-rectangle record)))
         (with-bounding-rectangle* (x1 y1 x2 y2) region
           (if (output-record-ancestor-p (stream-output-history stream) record)
               (progn
                 (delete-output-record record (output-record-parent record))
  -              (with-output-recording-options (stream :record nil)
  -                (draw-rectangle* stream x1 y1 x2 y2 :ink +background-ink+))
  +              (draw-rectangle* stream x1 y1 x2 y2 :ink +background-ink+)
                 (stream-replay stream region))
               (when errorp
                 (error "~S is not contained in ~S." record stream)))))))
  
positive.code:                       ;; fallback to the sheet's region for +everwhere+.
                        (sheet-region stream)
                        (bounding-rectangle region))))
        (with-bounding-rectangle* (x1 y1 x2 y2) region
          (with-output-recording-options (stream :record nil)
            (draw-rectangle* stream x1 y1 x2 y2 :filled t :ink +background-ink+)))
        (stream-replay stream region))))
  
  (defmethod scroll-extent :around ((stream output-recording-stream) x y)
    (declare (ignore x y))
  
negative.code:     (return-from replay (replay record (encapsulating-stream-stream stream) region)))
    (stream-close-text-output-record stream)
    (when (stream-drawing-p stream)
      (with-output-recording-options (stream :record nil)
        (with-sheet-medium (medium stream)
          (letf (((cursor-visibility (stream-text-cursor stream)) nil) ;; FIXME?
                 ((stream-cursor-position stream) (values 0 0))
                 ;; Is there a better value to bind to baseline?
                 ((slot-value stream 'baseline) (slot-value stream 'baseline))
                 ((medium-transformation medium) +identity-transformation+))
            (replay-output-record record stream region))))))
  
  (defmethod replay-output-record ((record compound-output-record) stream
                                   &optional region (x-offset 0) (y-offset 0))
  