anchor.diff:      space))
   
   (defmethod allocate-space ((rack vrack-pane) width height)
  -  (let ((h-percent (/ width (space-requirement-width (pane-space-requirement rack))))
  -	(v-percent (/ height (space-requirement-height (pane-space-requirement rack))))
  +  (let ((v-percent (/ height (space-requirement-height (pane-space-requirement rack))))
   	(y 0))
       (loop for child in (sheet-children rack)
   	for request = (pane-space-requirement child)
  -	for new-width = (floor (* h-percent (space-requirement-width request)))
   	for new-height = (floor (* v-percent (space-requirement-height request)))
   	do (setf (sheet-region child)
   	     (make-bounding-rectangle 0 y width (+ y new-height)))
  -	   (allocate-space child new-width new-height)
  +	   (allocate-space child width new-height)
   	   (incf y new-height))))
   
   
  
positive.code: 				       &key contents
  				       &allow-other-keys)
    (declare (ignore args))
    (loop for children in contents
  	do (loop for child in children
  		 do (sheet-adopt-child table child)))
    (setf (table-pane-number table) (length (first contents))))
  
  ;(defmethod initialize-instance :after ((table table-pane)
  ;				       &rest args
  ;				       &key contents
  ;				       &allow-other-keys)
  ;  (declare (ignore args))
  ;  (when contents
  ;    (if (reduce #'= (mapcar #'length contents))
  ;	(progn 
  ;	  (loop for children in contents
  ;		do (loop for child in children
  ;			 do (sheet-adopt-child table child)))
  ;	  (setf (table-pane-number table) (length (first contents))))
  ;	(error "The variable contents hasn't the good format"))))
  
  (defmacro tabling ((&rest options) &body contents)
    `(if (pane-grid-p (list ,@contents))
  
negative.code: 
  (defmethod allocate-space ((rack hrack-pane) width height)
    (let ((h-percent (/ width (space-requirement-width (pane-space-requirement rack))))
  	(x 0))
      (loop for child in (sheet-children rack)
  	for request = (pane-space-requirement child)
  	for new-width = (floor (* h-percent (space-requirement-width request)))
  	do (setf (sheet-region child)
  	     (make-bounding-rectangle x 0 (+ x new-width) height))
  	   (allocate-space child new-width height)
  	   (incf x new-width))))
  
  
  