plugin=diff is not implemented.
http://yellow.ribbon.to/~tuotehhou/index.php?%2BWindows%2B%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB%E3%82%B5%E3%82%A4%E3%82%BA%E3%81%AE%E5%8F%96%E5%BE%97
plugin=diff is not implemented.