anchor.diff:  (defmethod (setf sheet-transformation) :around (transformation (sheet basic-sheet))
     (let ((old-transformation (sheet-transformation sheet)))
       (unless (transformation-equal transformation old-transformation)
  -      (let ((*inhibit-dispatch-repaint* nil)) ; broken, don't use
  +      (with-inhibited-dispatch-repaint ()
           (call-next-method))
         (when (sheet-viewable-p sheet)
           (let* ((region (sheet-region sheet))
  
positive.code: 
  (in-package :clim-internals)
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Repaint protocol functions.
  
  (defmethod dispatch-repaint ((sheet graft) region)
    (declare (ignore sheet region)))
  
  ;;; Internal flag used in sheets module. We could make it a macro which
  ;;; accumulates regions to repaint with region-union and at the end repaints
  ;;; whole bunch at one go. Could be useful for presentation highlighting when we
  ;;; have many small areas to redraw. That could improve the performance.
  (defvar *inhibit-dispatch-repaint* nil
    "Used when we plan to repaint whole sheet and we suspect that children may
  want to do the same.")
  
  (defmethod dispatch-repaint :around ((sheet basic-sheet) region)
    (unless *inhibit-dispatch-repaint* (call-next-method)))
  
  (defmethod queue-repaint ((sheet basic-sheet) (event window-repaint-event))
    (queue-event sheet event))
  
negative.code: (defun %set-sheet-region-and-transformation (sheet region transformation)
    (let ((old-transformation (sheet-transformation sheet))
          (old-region (sheet-region sheet)))
      (with-inhibited-dispatch-repaint ()
        (setf (sheet-region sheet) region
              (sheet-transformation sheet) transformation))
      (when (sheet-viewable-p sheet)
  