anchor.diff:  
   (defmethod allocate-space ((pane label-pane) width height)
     (multiple-value-bind (right top left bottom) (label-pane-margins pane)
  -    (alexandria:when-let ((child (first (sheet-children pane))))
  +    (alexandria:when-let ((child (sheet-child pane)))
         (multiple-value-bind (x1 y1 x2 y2) (values 0 0 width height)
           (move-sheet child (+ x1 left) (+ y1 top))
           (allocate-space child
  
positive.code:                 ;; ### this other test below seems to be neccessary since
                  ;;     somebody decided that (NIL) is a valid return value
                  ;;     from sheet-children. --GB 2002-11-10
                  (first (sheet-children pane)))
             (let ((sr2 (compose-space (first (sheet-children pane)))))
               (multiple-value-bind (right top left bottom) (label-pane-margins pane)
                 (make-space-requirement
  
negative.code: 
  ;;; LABEL PANE
  
  (defclass label-pane (single-child-composite-pane)
    ((label :type string
            :initarg :label
            :accessor clime:label-pane-label
  