anchor.diff:                         :min-value 0
                          :max-value 1))
         (sheet-adopt-child pane vscrollbar))
  -    (when (not (eq scroll-bar :vertical))
  +    (when (member scroll-bar '(:horizontal t))
         (setq hscrollbar
               (make-pane 'scroll-bar-pane
                          :orientation :horizontal
  
positive.code:   (sheet-adopt-child pane (first contents))
    (with-slots (scroll-bar viewport vscrollbar hscrollbar) pane
      (setq viewport (first (sheet-children pane)))
      (when (not (eq scroll-bar :horizontal))
        (setq vscrollbar
              (make-pane 'scroll-bar-pane
                         :orientation :vertical
  
negative.code: (defparameter *scrollbar-thickness* 17)
  
  (defclass scroller-pane (composite-pane)
    ((scroll-bar :type (member t :vertical :horizontal nil)
                 ;; ### Note: I added NIL here, so that the application
                 ;; programmer can switch off scroll bars alltogether. 
                 ;; The spec though has it neither in the description of
                 ;; SCROLLER-PANE, nor in the description of
                 ;; MAKE-CLIM-STREAM-PANE, but in OPEN-WINDOW-STREAM.
                 ;;
                 ;; One might argue that in case of no scroll-bars the
                 ;; application programmer can just skip the scroller
                 ;; pane altogether. But I think that the then needed
                 ;; special casing on having a scroller pane or a bare
                 ;; viewport at hand is an extra burden, that can be
                 ;; avoided.
                 ;; --GB 2005-11-29
                 :initform t
                 :initarg :scroll-bar
                 :accessor scroller-pane-scroll-bar)
     (viewport   :initform nil)
     (vscrollbar :initform nil)
     (hscrollbar :initform nil)
  