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:       (note-tab-page-changed layout page))))
  
  (defmethod note-tab-page-changed ((layout tab-layout) page)
    nil)
  
  ;;; GTK+ distinguishes between children user code creates and wants to
  ;;; see, and "internal" children the container creates and mostly hides
  ;;; from the user.  Let's steal that concept to ignore the header pane.
  (defgeneric internal-child-p (child parent))
  
  (defmethod internal-child-p (child (parent tab-layout))
    nil)
  
  (defun page-successor (page)
  
negative.code: 
  (defmethod sheet-disown-child :before ((parent tab-layout) child &key errorp)
    (declare (ignore errorp))
    (alexandria:when-let ((page (sheet-to-page child)))
      (setf (slot-value parent 'pages) (remove page (tab-layout-pages parent))
            (tab-page-tab-layout page) nil)
      (let* (;; tab-layout-enabled-page may be NIL!
             (current-page (tab-layout-enabled-page parent))
             (currentp (equal child (tab-page-pane current-page)))
             (successor
              (when currentp
                (page-successor current-page))))
        (when currentp
          (setf (tab-layout-enabled-page parent) successor)))))
  
  (defun sheet-to-page (sheet)
    "For a SHEET that is a child of a tab layout, return the page corresponding
  