anchor.diff:  (defmethod (setf sheet-region) :around (region (sheet basic-sheet))
     (let ((old-region (sheet-region sheet)))
       (unless (region-equal region old-region)
  -      (let ((*inhibit-dispatch-repaint* nil)) ; broken, don't use
  +      (with-inhibited-dispatch-repaint ()
           (call-next-method))
         (when (sheet-viewable-p sheet)
           (dispatch-repaint (sheet-parent sheet)
  
positive.code: (defun %set-sheet-region-and-transformation (sheet region transformation)
    (let ((old-transformation (sheet-transformation sheet))
          (old-region (sheet-region sheet)))
      (let ((*inhibit-dispatch-repaint* nil)) ; broken, don't use
        (setf (sheet-region sheet) region
              (sheet-transformation sheet) transformation))
      (when (sheet-viewable-p sheet)
  
negative.code: (defmethod (setf sheet-transformation) :around (transformation (sheet basic-sheet))
    (let ((old-transformation (sheet-transformation sheet)))
      (unless (transformation-equal transformation old-transformation)
        (with-inhibited-dispatch-repaint ()
          (call-next-method))
        (when (sheet-viewable-p sheet)
          (let* ((region (sheet-region sheet))
  