anchor.diff:  
   
   (defmethod allocate-space ((grid grid-pane) width height)
  -  (setf (sheet-region grid) (make-bounding-rectangle 0 0 width height))
  +  (set-width-and-height grid width height)
     (let* ((new-height (/ height (/ (length (sheet-children grid)) (table-pane-number grid))))
   	 (new-width (/ width (table-pane-number grid)))
   	 (contents (format-children (sheet-children grid) (table-pane-number grid)))
  
positive.code: (defmethod ask-space-children ((composite composite-pane))
    (mapcar #'compose-space (sheet-children composite)))
  
  (defmethod compute-space ((composite composite-pane))
    (let ((space (make-space-requirement)))
      (loop for child in (sheet-children composite)
  
negative.code:     space))
  
  (defmethod allocate-space ((box hbox-pane) width height)
    (set-width-and-height box width height)
    (let ((h-percent (/ width (space-requirement-width (pane-space-requirement box))))
  	(v-percent (/ height (space-requirement-height (pane-space-requirement box))))
  	(x 0))
  