anchor.diff:                (xlib:gcontext-clip-y gc) 0
                 (xlib:gcontext-ts-x gc) 0
                 (xlib:gcontext-ts-y gc) 0
  -              (xlib:gcontext-clip-mask gc) (list 0 0 w h))
  +              (xlib:gcontext-clip-mask gc) mask)
           gc))))
   
   (defmethod design-gcontext ((medium clx-medium) (ink climi::rectangular-tile))
  
positive.code:     (medium-draw-line* medium x1 y1 x2 y2)))
  
  (defmethod medium-draw-polygon* ((medium clx-medium) coord-seq closed filled)
    (assert (evenp (length coord-seq)))
    (let ((coord-seq (coerce coord-seq 'list))) ;XXX optimize this
      (with-transformed-positions ((sheet-native-transformation
  				  (medium-sheet medium))
  				 coord-seq)
        (setq coord-seq (mapcar #'round-coordinate coord-seq))
        (with-clx-graphics (medium)
  	(xlib:draw-lines mirror gc
  			 (if closed
  			     (append coord-seq (list (first coord-seq)
  						     (second coord-seq)))
  			     coord-seq)
  			 :fill-p filled)))))
  
  (defmethod medium-draw-rectangle* ((medium clx-medium) left top right bottom filled)
    (let ((tr (sheet-native-transformation (medium-sheet medium))))
      (with-transformed-position (tr left top)
        (with-transformed-position (tr right bottom)
  
negative.code:          (inks  (slot-value ink 'climi::designs))
           (w     (array-dimension array 1))
           (h     (array-dimension array 0)))
      (let* ((pm   (allocate-pixmap (first (port-grafts (port medium))) w h))
             (mask (xlib:create-pixmap :drawable (port-lookup-mirror
                                                  (port medium)
                                                  (first (port-grafts (port medium))))
                                       :depth 1
                                       :width w
                                       :height h))
             (mask-gc (xlib:create-gcontext :drawable mask :foreground 1)))
        (xlib:draw-rectangle mask mask-gc 0 0 w h t)
        (setf (xlib:gcontext-foreground mask-gc) 0)
        (dotimes (y h)
          (dotimes (x w)
            (let ((ink (elt inks (aref array y x))))
              (cond ((eq ink +transparent-ink+)
                     (xlib:draw-point mask mask-gc x y))
                    (t
                     (draw-point* pm x y :ink ink))))))
        (xlib:free-gcontext mask-gc)
        (let ((gc (xlib:create-gcontext :drawable (port-lookup-mirror (port medium) (medium-sheet medium)))))
          (setf (xlib:gcontext-fill-style gc) :tiled
                (xlib:gcontext-tile gc) (port-lookup-mirror (port pm) pm)
  