anchor.diff:    (:documentation ""))
   
   (defmethod compose-space ((rack vrack-pane))
  -  (mapc #'compose-space (sheet-children rack))
  -  (loop with space = (make-space-requirement 
  -		      :max-width (sr-max-width (car (sheet-children rack))))
  -	for child in (sheet-children rack)
  -	for request = (pane-space-requirement child)
  -	sum (get-pane-height child) into sum-height
  -	do (setf (space-requirement-width space)
  -		 (max (space-requirement-width space)
  -		      (space-requirement-width request)))
  -	   (setf (space-requirement-max-width space)
  -		 (min (space-requirement-max-width space)
  -		      (space-requirement-max-width request)))
  -	   (setf (space-requirement-min-width space)
  -		 (max (space-requirement-min-width space)
  -		      (space-requirement-min-width request)))
  -	   (incf (space-requirement-height space)
  -		 (space-requirement-height request))
  -	   (incf (space-requirement-max-height space)
  -		 (space-requirement-max-height request))
  -	   (incf (space-requirement-min-height space)
  -		 (space-requirement-min-height request))
  -	finally (progn
  -		  (setf (slot-value rack 'sum-height) sum-height)
  -		  (return space))))
  +  (loop for child in (sheet-children rack)
  +        for sr = (compose-space child)
  +        maximize (space-requirement-width sr) into width
  +        maximize (space-requirement-min-width sr) into min-width
  +        minimize (space-requirement-max-width sr) into max-width
  +        sum (space-requirement-height sr) into height
  +        sum (space-requirement-min-height sr) into min-height
  +        sum (space-requirement-max-height sr) into max-height
  +        finally
  +        (progn
  +          (setf (slot-value rack 'sum-height) (max min-height height))
  +          (return (make-space-requirement
  +                   :min-width  min-width
  +                   :width      (max min-width width)
  +                   :max-width  (max max-height width)
  +                   :min-height min-height
  +                   :height     (max min-height height)
  +                   :max-height (max max-height height))) )))
   
   (defmethod compute-extremum ((rack vrack-pane))
     (make-extremums-children-ratio-height rack (sheet-children rack)))
  
positive.code:     :max-height max-height
      :min-height min-height))
  
  (defmethod space-requirement-components ((space-req space-requirement))
    (with-slots (width min-width max-width height min-height max-height) space-req
      (values width min-width max-width height min-height max-height)))
  
  
negative.code:   (:documentation ""))
  
  (defmethod compose-space ((rack hrack-pane))
    (loop for child in (sheet-children rack)
          for sr = (compose-space child)
          maximize (space-requirement-height sr) into height
          maximize (space-requirement-min-height sr) into min-height
          minimize (space-requirement-max-height sr) into max-height
          sum (space-requirement-width sr) into width
          sum (space-requirement-min-width sr) into min-width
          sum (space-requirement-max-width sr) into max-width
          finally
          (progn
            (setf (slot-value rack 'sum-width) (max min-width width))
            (return (make-space-requirement
                     :min-height  min-height
                     :height      (max min-height height)
                     :max-height  (max max-width height)
                     :min-width min-width
                     :width     (max min-width width)
                     :max-width (max max-width width))) )))
  
  (defmethod compute-extremum ((rack hrack-pane))
    (make-extremums-children-ratio-width rack (sheet-children rack)))
  