anchor.diff:    (let ((tr (medium-transformation stream)))
       (if (rectilinear-transformation-p tr)
           (generate-medium-recording-body draw-rectangles-output-record
  -					medium-draw-rectangles*
  +                                        medium-draw-rectangles*
                                           (coord-seq filled))
  -	(do-sequence ((left top right bottom) coord-seq)
  +        (do-sequence ((left top right bottom) coord-seq)
             (medium-draw-polygon* stream (vector left top
                                                  left bottom
                                                  right bottom
  
positive.code:     (apply function (tree-output-record-entry-record child) function-args)))
  
  (defmethod map-over-output-records-1 (function (record standard-tree-output-record) function-args)
    (map-over-tree-output-records function record 
      (%record-to-spatial-tree-rectangle record) :most-recent-last
                                  function-args))
  
  (defmethod map-over-output-records-containing-position 
      (function (record standard-tree-output-record) x y 
       &optional x-offset y-offset &rest function-args)
    (declare (ignore x-offset y-offset))
    (map-over-tree-output-records function record 
      (rectangles:make-rectangle :lows `(,x ,y) :highs `(,x ,y)) :most-recent-first
                                  function-args)) 
  
  (defmethod map-over-output-records-overlapping-region
      (function (record standard-tree-output-record) region 
       &optional x-offset y-offset &rest function-args)
    (declare (ignore x-offset y-offset))
    (typecase region
  
negative.code: (defun coord-seq-bounds (coord-seq border)
    (setf border (ceiling border))
    (let* ((min-x (elt coord-seq 0))
           (min-y (elt coord-seq 1))
           (max-x min-x)
           (max-y min-y))
      (do-sequence ((x y) coord-seq)
        (minf min-x x)
        (minf min-y y)
  