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:     space))
  
  (defmethod allocate-space ((box hbox-pane) width height)
    (setf (sheet-region box) (make-bounding-rectangle 0 0 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))
  
negative.code: 			    :height 200
  			    :max-height 200)))
  
  (defun set-width-and-height (rectangular-sheet width height)
    (multiple-value-bind (x1 y1)
        (rectangle-edges* (sheet-region rectangular-sheet))
      (setf (sheet-region rectangular-sheet)
  	  (make-rectangle* x1 y1 (+ x1 width) (+ y1 height)))))
  
  ;;; FIXME: this should be done for each type of pane
  (defmethod allocate-space ((pane pane) width height)
    (set-width-and-height pane width height))
  
  (defmethod change-space-requirements ((pane pane) &rest rest)
    (declare (ignore rest))
  