plugin=diff is not implemented.
http://yellow.ribbon.to/~tuotehhou/index.php?%2BWPF%2B%E5%9F%8B%E3%82%81%E8%BE%BC%E3%81%BF%E3%83%AA%E3%82%BD%E3%83%BC%E3%82%B9%E3%81%AE%E3%82%A2%E3%82%AF%E3%82%BB%E3%82%B9
plugin=diff is not implemented.