anchor.diff:                       (eq (line-style-unit line-style)
                            (line-style-unit old-line-style)))
             (setf (xlib:gcontext-line-width gc)
  -                (line-style-effective-thickness line-style medium)))
  +                (round (line-style-effective-thickness line-style medium))))
           (unless (eq (line-style-cap-shape line-style)
                       (line-style-cap-shape old-line-style))
             (setf (xlib:gcontext-cap-style gc)
  
positive.code:         (unless (eq (line-style-joint-shape line-style)
                      (line-style-joint-shape old-line-style))
            (setf (xlib:gcontext-join-style gc)
                  (line-style-joint-shape line-style)))
          ;; we could do better here by comparing elements of the vector
          ;; -RS 2001-08-24
          (unless (and (eq (line-style-dashes line-style)
                           (line-style-dashes old-line-style))
                       (eq (line-style-unit line-style)
                           (line-style-unit old-line-style)))
            (setf (xlib:gcontext-line-style gc)
                  (if (line-style-dashes line-style) :dash :solid)
                  (xlib:gcontext-dashes gc)
                  (case (line-style-dashes line-style)
                    ((t nil) (round (* (line-style-scale line-style medium) 3)))
                    (otherwise (line-style-effective-dashes line-style medium)))))))))
  
  (defun %clip-region-pixmap (medium mask mask-gc clipping-region x1 y1 width height)
    (typecase clipping-region
  
negative.code:                                 (medium-sheet medium))
                                 coord-seq)
      (with-clx-graphics () medium
        (let ((diameter (line-style-effective-thickness line-style medium)))
          (if (< diameter 2)
              (do-sequence ((x y) coord-seq)
                (let ((x (round-coordinate x))
                      (y (round-coordinate y)))
                  (when (and (typep x '(signed-byte 16))
                             (typep y '(signed-byte 16)))
                    (xlib:draw-point mirror gc x y))))
              (let ((radius   (round diameter 2))
                    (diameter (round diameter)))
                (do-sequence ((x y) coord-seq)
                  (let ((min-x (round-coordinate (- x radius)))
                        (min-y (round-coordinate (- y radius))))
                    (when (and (typep min-x '(signed-byte 16))
                               (typep min-y '(signed-byte 16)))
                      (xlib:draw-arc mirror gc min-x min-y
                                     diameter diameter
                                     0 (* 2 pi) t))))))))))
  
  (defmethod medium-draw-line* ((medium clx-medium) x1 y1 x2 y2)
    (let ((tr (sheet-native-transformation (medium-sheet medium))))
  