anchor.diff:  
   (defclass clim-extensions::box-adjuster-gadget
                  (standard-gadget 3d-border-mixin orientation-from-parent-mixin)
  -  ((drag-from :initform nil))
  +  ((drag-from :initform nil)
  +   (left-sr)
  +   (left-peer)
  +   (right-sr)
  +   (right-peer))
     (:default-initargs :background *3d-inner-color*))
   
   (defmethod compose-space ((gadget clim-extensions:box-adjuster-gadget)
  
positive.code:   (if (eq (orientation gadget) :vertical)
        (make-space-requirement :min-width 6 :width 6 :max-width 6
                                :min-height 1 :height 1)
      (make-space-requirement :min-height 6 :height 6 :max-height 6
                              :min-width 1 :width 1)))
  
  (defmethod handle-event ((gadget clim-extensions:box-adjuster-gadget)
                           (event pointer-button-press-event))
    (setf (slot-value gadget 'drag-from)
          (if (eq (orientation gadget) :vertical)
              (pointer-event-native-graft-x event)
            (pointer-event-native-graft-y event))))
  
  (defmethod handle-event ((gadget clim-extensions:box-adjuster-gadget)
                           (event pointer-button-release-event))
  
negative.code:           (values (space-requirement-width sr)
                    (space-requirement-max-width sr)
                    (space-requirement-min-width sr))
            (values (space-requirement-height sr)
                    (space-requirement-max-height sr)
                    (space-requirement-min-height sr)))
      (let ((new-major (max major-min (min major-max (+ major delta)))))
        (if (eq orientation :vertical)
            (change-space-requirements pane :width new-major)
            (change-space-requirements pane :height new-major))
        (- new-major major))))
  
  (defmethod handle-event ((gadget clim-extensions:box-adjuster-gadget)
                           (event pointer-motion-event)
                           &aux (orientation (orientation gadget)))
    (with-slots (drag-from left-peer left-sr right-peer right-sr) gadget
      (when (and drag-from (typep (sheet-parent gadget) 'box-layout-mixin))
        (let* ((major-pos (if (eq orientation :vertical)
                              (pointer-event-native-graft-x event)
                              (pointer-event-native-graft-y event)))
               (delta (- major-pos drag-from)))
          (changing-space-requirements (:resize-frame nil)
            (adjust-space-requirement left-peer  left-sr  orientation delta)
            (adjust-space-requirement right-peer right-sr orientation (- delta)))))))
  