anchor.diff:                    (if (< (ldb (byte 8 0) elt) #x80)
                         (setf (aref mdata y x) 0)
                         (setf (aref mdata y x) 1)))))
  -      (unless (or (>= width 2048) (>= height 2048)) ;### CLX bug
  -        (xlib:put-image mm mm-gc mm-image :src-x 0 :src-y 0 :x 0 :y 0
  -                        :width width :height height :bitmap-p nil))
  +      (put-image-recursively mm mm-gc mm-image width height 0 0)
         (xlib:free-gcontext mm-gc)
         (push #'(lambda () (xlib:free-pixmap mm)) ^cleanup)
         mm)))
  
positive.code: 
  (defmethod medium-draw-rectangle* ((medium clx-medium) left top right bottom filled
                                     &aux (ink (medium-ink medium)))
    (let ((tr (sheet-native-transformation (medium-sheet medium))))
      (with-transformed-position (tr left top)
        (with-transformed-position (tr right bottom)
  
negative.code: 
  
  (defun put-image-recursively (pixmap pixmap-context pixmap-image width height x0 y0)
    (labels ((put-partial-image (width height x0 y0)
               (cond
                 ((and (< width +x11-pixmap-dimension-limit+) (< height +x11-pixmap-dimension-limit+))
                  (xlib:put-image pixmap pixmap-context pixmap-image
                                  :src-x x0 :src-y y0 :x x0 :y y0
                                  :width width :height height))
                 ((> width height)
                  (put-partial-image (ceiling width 2) height x0 y0)
                  (put-partial-image (floor width 2) height (+ x0 (ceiling width 2)) y0))
                 (T
                  (put-partial-image width (ceiling height 2) x0 y0)
                  (put-partial-image width (floor height 2) x0 (+ y0 (ceiling height 2)))))))
      (put-partial-image width height x0 y0)))
  
  ;;; XXX: both PM and MM pixmaps should be freed with (xlib:free-pixmap pixmap)
  ;;; when not used. We do not do that right now.
  (defun compute-rgb-mask (drawable image)
  