plugin=diff is not implemented.
http://yellow.ribbon.to/~tuotehhou/index.php?%2BSL%2BWCF%E3%81%AB%E3%82%88%E3%82%8B%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB%E3%81%AE%E3%82%A2%E3%83%83%E3%83%97%E3%83%AD%E3%83%BC%E3%83%89
plugin=diff is not implemented.