anchor.diff:                              mouse-wheel-scroll-mixin
                               cut-and-paste-mixin)
     ((redisplay-needed :initarg :display-time) 
  -   (scroll-bars :type (member t :vertical :horizontal nil)
  +   (scroll-bars :type scroll-bar-spec ; (member t :vertical :horizontal nil)
   		:initform nil
   		:initarg :scroll-bars
   		:accessor pane-scroll-bars)
  
positive.code: ;;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  ;;; Boston, MA  02111-1307  USA.
  
  ;;; $Id: panes.lisp,v 1.173 2006-11-08 01:18:22 thenriksen Exp $
  
  (in-package :clim-internals)
  
  
negative.code:     (when (first (sheet-children viewport))
        (setf (slot-value pane 'background)  ;### hmm ...
              (pane-background (first (sheet-children viewport)))))
      ;; make sure that we have ok options for the scroll-bar argument...
      (check-type scroll-bar scroll-bar-spec) ; (member :vertical :horizontal :both t nil))
      (when (member scroll-bar '(:vertical :both t))
        (setq vscrollbar
              (make-pane 'scroll-bar-pane
                         :orientation :vertical
  