plugin=diff is not implemented.
http://yellow.ribbon.to/~tuotehhou/index.php?%2BWCF%2B%E7%B0%A1%E5%8D%98%E7%9A%84%E3%81%AA%E8%A8%AD%E5%AE%9A%E3%82%B5%E3%83%B3%E3%83%97%E3%83%AB
plugin=diff is not implemented.