anchor.diff:  ;;; LABEL PANE
   
   (defclass label-pane (composite-pane  permanent-medium-sheet-output-mixin)
  -  ((label :type string :initarg :label :accessor label-pane-label)
  +  ((label :type string
  +          :initarg :label
  +          :accessor label-pane-label
  +          :initform "")
      (alignment :type (member :bottom :top)
                 :initform :top
                 :initarg :label-alignment
  
positive.code:     :initarg  :width
      :initform nil
      :reader   pane-user-width
      :type     spacing-value)
     (user-min-width 
      :initarg :min-width
      :initform nil
      :reader   pane-user-min-width
      :type     spacing-value)
     (user-max-width
      :initarg :max-width
      :initform nil
      :reader   pane-user-max-width
      :type     spacing-value)
     (user-height
      :initarg :height
      :initform nil
      :reader   pane-user-height
      :type     spacing-value)
     (user-min-height
      :initarg :min-height
      :initform nil
      :reader   pane-user-min-height
      :type     spacing-value)
     (user-max-height
      :initarg :max-height
      :initform nil
      :reader   pane-user-max-height
      :type     spacing-value)
     (x-spacing
      :initarg :x-spacing
      :initform 0
      :reader   pane-x-spacing
      :type     spacing-value)
     (y-spacing
      :initarg :y-spacing
      :initform 0
      :reader   pane-y-spacing
      :type     spacing-value))
    (:documentation
     "Mixin class for panes which offer the standard user space requirements options."))
  
  
negative.code: ;;;  (c) copyright 2001 by
  ;;;           Lionel Salabartan (salabart@emi.u-bordeaux.fr)
  ;;;           Arnaud Rouanet (rouanet@emi.u-bordeaux.fr)
  ;;;  (c) copyright 2002, 2003 by
  ;;;           Gilbert Baumann <unk6@rz.uni-karlsruhe.de>
  
  ;;; This library is free software; you can redistribute it and/or
  