anchor.diff:                 ,@options
                  :contents (list ,@(mapcar (lambda (content)
                                              (cond ((and (consp content)
  -                                                       (realp (first content)))
  +                                                       (or (realp (first content))
  +                                                           (member (first content) '(+fill+ :fill))))
                                                     `(list ',(first content)
                                                            ,(second content)))
                                                    (t
  
positive.code: 
   (defmethod initialize-instance :after ((pane xbox-pane) &key contents &allow-other-keys)
     (let ((children (mapcar (lambda (content)
                               (cond ((panep content)
                                      content)
                                     ;;
                                     ((or (eql content +fill+) (eql content '+fill+))
                                      (let ((child (make-instance 'null-pane)))
                                        (setf (constraint-slot pane child 'fill-p) t)
                                        child))
                                     ;;
  
negative.code: ;;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  ;;; Boston, MA  02111-1307  USA.
  
  ;;; $Id: panes.lisp,v 1.94 2002-07-31 18:54:48 gilbert Exp $
  
  (in-package :CLIM-INTERNALS)
  
  