anchor.diff:  
   ;; Top-level-sheet
   
  +;; this is evil.
   (defmethod compute-extremum :after ((pane top-level-sheet-pane))
     (with-slots (space-requirement) pane
       (setf (xlib:wm-normal-hints (sheet-direct-mirror pane))
  
positive.code:   (make-translation-transformation (xlib:drawable-x mirror)
                                     (xlib:drawable-y mirror)))
  
  (defmethod port-set-sheet-region ((port clx-port) (graft graft) region)
    (declare (ignore region))
    nil)
  
  (defmethod port-set-sheet-region ((port clx-port) (sheet mirrored-sheet-mixin) region)
    (let ((mirror (sheet-direct-mirror sheet)))
      (multiple-value-bind (x1 y1 x2 y2) (bounding-rectangle* region)
        (setf (xlib:drawable-width mirror) (round (- x2 x1))
  	    (xlib:drawable-height mirror) (round (- y2 y1))))))
  
  (defmethod port-set-sheet-transformation ((port clx-port) (graft graft) transformation)
    (declare (ignore transformation))
    nil)
  
  (defmethod port-set-sheet-transformation ((port clx-port) (pane application-pane) transformation)
    (declare (ignore transformation))
    nil)
  
  (defmethod port-set-sheet-transformation ((port clx-port) (pane interactor-pane) transformation)
    (declare (ignore transformation))
    nil)
  
  (defmethod port-set-sheet-transformation ((port clx-port) (sheet mirrored-sheet-mixin) transformation)
    (let ((mirror (sheet-direct-mirror sheet)))
      (multiple-value-bind (x y) (transform-position transformation 0 0)
        (setf (xlib:drawable-x mirror) (round x)
  	    (xlib:drawable-y mirror) (round y)))))
  
  (defmethod destroy-port :before ((port clx-port))
    (xlib:close-display (clx-port-display port)))
  
negative.code:          :name (format nil "~S's event process." port))))
      ))
  
  #+NIL
  (defmethod (setf sheet-mirror-transformation) :after (new-value (sheet mirrored-sheet-mixin))
    )
  
  (defun invent-sheet-mirror-transformation-and-region (sheet)
    ;; -> tr region
    (let* ((r (sheet-region sheet))
           (r* (transform-region
                (sheet-native-transformation (sheet-parent sheet))
                (transform-region (sheet-transformation sheet) r)))
           #+NIL
           (r*
            (bounding-rectangle
             (region-intersection r*
                                  (make-rectangle* 0 0
                                                   (port-mirror-width (port sheet) (sheet-parent sheet))
                                                   (port-mirror-height (port sheet) (sheet-parent sheet))))))
           (mirror-transformation
            (if (region-equal r* +nowhere+)
                (make-translation-transformation 0 0)
              (make-translation-transformation 
               (bounding-rectangle-min-x r*)
               (bounding-rectangle-min-y r*))))
           (mirror-region
            (untransform-region mirror-transformation r*)))
      (values
       mirror-transformation
       mirror-region)))
     
  
  (defun realize-mirror-aux (port sheet
  				&key (width 100) (height 100) (x 0) (y 0)
  				(border-width 0) (border 0)
  