plugin=diff is not implemented.
http://yellow.ribbon.to/~tuotehhou/index.php?%2BVB6%2BMSCOMCTL.OCX%E3%81%8C%E8%AA%AD%E3%81%BF%E8%BE%BC%E3%82%81%E3%81%BE%E3%81%9B%E3%82%93
plugin=diff is not implemented.