anchor.diff:                (min-y (round-coordinate (min top bottom)))
                 (max-x (round-coordinate (max left right)))
                 (max-y (round-coordinate (max top bottom))))
  -          (xlib:draw-rectangle (or (medium-buffer medium)
  -                                   (port-lookup-mirror (port medium)
  -                                                       (medium-sheet medium)))
  +          (xlib:draw-rectangle (port-lookup-mirror (port medium)
  +                                                   (medium-sheet medium))
                                  (medium-gcontext medium (medium-background medium))
                                  (max #x-8000 (min #x7fff min-x))
                                  (max #x-8000 (min #x7fff min-y))
  
positive.code:                           (medium-gcontext from-drawable +background-ink+)
                            (round-coordinate from-x) (round-coordinate from-y)
                            (round width) (round height)
                            (or (medium-buffer to-drawable)
                                (sheet-xmirror (medium-sheet to-drawable)))
                            (round-coordinate to-x) (round-coordinate to-y)))))))
  
  (defmethod medium-copy-area ((from-drawable clx-medium) from-x from-y width height
  
negative.code:   ((gc :initform nil)
     (last-medium-device-region :initform nil
                                :accessor last-medium-device-region)
     ;; CLIPPING-REGION-TMP is reused to avoid consing in the most common case
     ;; when configuring the clipping region.n
     (clipping-region-tmp :initform (vector 0 0 0 0))))
  
  
  