anchor.diff:  
   ; (defclass aspect-frame (frame)
   ;   ((xalign
  -;     :allocation :arg
  +;     :allocation :param
   ;     :accessor aspect-frame-xalign
   ;     :initarg :xalign
   ;     :type single-float)
   ;    (yalign
  -;     :allocation :arg
  +;     :allocation :param
   ;     :accessor aspect-frame-yalign
   ;     :initarg :yalign
   ;     :type single-float)
   ;    (ratio
  -;     :allocation :arg
  +;     :allocation :param
   ;     :accessor aspect-frame-ratio
   ;     :initarg :ratio
   ;     :type single-float)
   ;    (obey-child
  -;     :allocation :arg
  +;     :allocation :param
   ;     :accessor aspect-frame-obey-child-p
   ;     :initarg :obey-child
   ;     :type boolean))
  
positive.code: 
  (defclass box (container)
    ((spacing
      :allocation :arg
      :accessor box-spacing
      :initarg :spacing
      :type int)
     (homogeneous
      :allocation :arg
      :accessor box-homogeneous-p
      :initarg :homogeneous
      :type boolean))
  
negative.code: 
  (defclass ruler (widget)
    ((lower
      :allocation :param
      :accessor ruler-lower
      :initarg :lower
      :type single-float)
     (upper
      :allocation :param
      :accessor ruler-upper
      :initarg :upper
      :type single-float)
     (position
      :allocation :param
      :accessor ruler-position
      :initarg :position
      :type single-float)
     (max-size
      :allocation :param
      :accessor ruler-max-size
      :initarg :max-size
      :type single-float)
  