anchor.diff:    (when (sheet-child pane)
       (allocate-space (sheet-child pane) width height)))
   
  -;;;; TOP-LEVEL-SHEET
  +;;; TOP-LEVEL-SHEET
   
   (defclass top-level-sheet-pane (composite-pane)
     ()
  
positive.code: 			 (max sx0 (min (- sx1 viewport-width)  (+ vx0 (* delta horizontal))))
  			 (max sy0 (min (- sy1 viewport-height) (+ vy0 (* delta vertical))))))))))
  
  ;; Note that handling this from dispatch-event is evil, and we shouldn't.
  (defmethod dispatch-event :around ((sheet mouse-wheel-scroll-mixin)
                                     (event pointer-button-press-event))
    (if (find-viewport-for-scroll sheet)
  
negative.code: 			 (event window-manager-delete-event))
    (frame-exit (pane-frame (event-sheet event))))
  
  ;;; UNMANAGED-TOP-LEVEL-SHEET PANE
  
  (defclass unmanaged-top-level-sheet-pane (top-level-sheet-pane)
    ()
  