anchor.diff:  ;;; presentation/command system integration
   
   (define-command (com-switch-to-tab-page
  -		 :command-table clim:global-command-table)
  +                 :command-table clim:global-command-table)
       ((page 'tab-page :prompt "Tab page"))
     (switch-to-page page))
   
   (define-presentation-to-command-translator switch-via-tab-button
       (tab-page com-switch-to-tab-page clim:global-command-table
  -	      :gesture :select
  -	      :documentation "Switch to this page"
  -	      :pointer-documentation "Switch to this page")
  +              :gesture :select
  +              :documentation "Switch to this page"
  +              :pointer-documentation "Switch to this page")
       (object)
     (list object))
   
  
positive.code:   (let ((ptypevar (gensym)))
      `(let ((,ptypevar ,default-presentation-type))
         (make-pane 'tab-layout
  		  :name ,(or name `',(gensym "tab-layout-"))
  		  :pages (list ,@(mapcar (lambda (spec)
  					   `(make-tab-page ,@spec
  							   :presentation-type
  					     ,ptypevar))
  					 body))
  		  ,@initargs))))
  
  (defun make-tab-page
      (title pane &key presentation-type drawing-options enabled-callback)
  
negative.code: (defun default-display-tab-header (tab-layout pane)
    (stream-increment-cursor-position pane 0 3)
    (draw-line* pane
                0
                17
                (1- (climi::pane-current-width pane))
                17
                :ink +black+)
    (mapc (lambda (page)
            (with-output-as-presentation
                (pane (tab-page-pane page)
                      (tab-page-presentation-type page))
              (present page 'tab-page :stream pane)))
          (tab-layout-pages tab-layout)))
  
  (defclass tab-bar-pane (application-pane)
    ()
  