anchor.diff:  	   #:with-tab-layout
              #:com-switch-to-tab-page
   	   #:com-remove-tab-page
  -	   #:internal-child-p
   	   #:note-tab-page-changed))
   
   (in-package #:clim-tab-layout)
  
positive.code: 
  (defmethod sheet-disown-child :before ((parent tab-layout) child &key errorp)
    (declare (ignore errorp))
    (unless (internal-child-p child parent)
      (let* ((page (sheet-to-page child))
  	   (current-page (tab-layout-enabled-page parent))
  	   (currentp (equal child (tab-page-pane current-page)))
  	   (successor
  	    (when currentp
  	      (page-successor current-page))))
        (setf (slot-value parent 'pages) (remove page (tab-layout-pages parent)))
        (when currentp
  	(setf (tab-layout-enabled-page parent) successor))
        (setf (tab-page-tab-layout page) nil))))
  
  (defun sheet-to-page (sheet)
    "For a SHEET that is a child of a tab layout, return the page corresponding
  
negative.code:       (note-tab-page-changed layout page))))
  
  (defmethod note-tab-page-changed ((layout tab-layout) page)
    nil)
  
  (defun page-successor (page)
  