anchor.diff:  
   (defclass meta-list-pane ()
     ((mode        :initarg :mode
  -                :initform :some-of
  +                :initform :exclusive
                   :reader list-pane-mode
                   :type (member :one-of :some-of))
      (items       :initarg :items
  
positive.code:         (changing-space-requirements (:resize-frame nil)
            (adjust-space-requirement left-peer  left-sr  orientation delta)
            (adjust-space-requirement right-peer right-sr orientation (- delta)))))))
  
negative.code: 
  ;; Why is there GADGET-LABEL-TEXT-STYLE? The spec says, that just the
  ;; pane's text-style should be borrowed.
  
  ;; RANGE-GADGET / RANGE-GADGET-MIXIN: same thing as with
  ;; ORIENTED-GADGET-MIXIN.
  