anchor.diff:  
   (defmethod compose-space ((pane scroller-pane) &key width height)
     (declare (ignore width height))
  -  (with-slots (viewport vscrollbar hscrollbar suggested-width suggested-height) pane
  +  (with-slots (viewport vscrollbar hscrollbar suggested-width suggested-height
  +               x-spacing y-spacing scroll-bar)
  +      pane
       (if viewport
           (let ((req
                  ; v-- where does this requirement come from?
                  ;     a: just an arbitrary default
   		(make-space-requirement
                   :width suggested-width :height suggested-height :max-width +fill+ :max-height +fill+
  -                :min-width 30
  -                :min-height 30)
  +                :min-width  (max (* 2 x-spacing) (if (null scroll-bar) 0 30))
  +                :min-height (max (* 2 y-spacing) (if (null scroll-bar) 0 30)))
   		#+nil
   		(make-space-requirement :height +fill+ :width +fill+)))
             (when vscrollbar
  
positive.code:      (values majors
               (mapcar (lambda (x) x minor) minors))))
  
    (defmethod box-layout-mixin/xically-allocate-space ((pane box-layout-mixin) real-width real-height)
     (with-slots (major-spacing) pane
       (multiple-value-bind (majors minors)
           (box-layout-mixin/xically-allocate-space-aux* pane real-width real-height)
         ;; now actually layout the children
         (let ((x 0))
           (loop
               for child in (box-layout-mixin-clients pane)
  
negative.code:                              ((lambda (major minor) height width) x 0)
                               ((lambda (major minor) width height) x 0)
                               ((lambda (major minor) height width) width real-width)
                               ((lambda (major minor) height width) real-height height) ))
               (incf x major)
               (incf x major-spacing))))))
  
   (defmethod box-layout-mixin/xically-allocate-space ((pane rack-layout-mixin) real-width real-height)
     (with-slots (major-spacing) pane
       (multiple-value-bind (majors minors)
           (box-layout-mixin/xically-allocate-space-aux* pane real-width real-height)
         (let ((x 0))
           (loop
               for child in (box-layout-mixin-clients pane)
               for major in majors
               for minor in minors
               do
               (when (box-client-pane child)
                 #+NIL
                 (format *trace-output* "~&;;   child ~S at 0, ~D ~D x ~D(~D)~%;;       ~S~%"
                         (box-client-pane child)
                         x width height real-height
                         (compose-space (box-client-pane child)))
                 (layout-child (box-client-pane child)
                               :expand
                               :expand
                               ((lambda (major minor) height width) x 0)
                               ((lambda (major minor) width height) x 0)
                               ((lambda (major minor) height width) width real-width)
                               ((lambda (major minor) height width) real-height height) ))
               (incf x major)
               (incf x major-spacing)))))))
  
  ;; #+nil
  (defmethod note-sheet-enabled :before ((pane pane))
  