Comment 1 for bug 698744

Here's a patch. I hope you won't mind that it's 7 years late :)

The technique is based on this article: http://www.evilmadscientist.com/article.php/visdiff . It integrates with mercurial, git, and subversion. And it doesn't show unprintable features like invisible attributes; you'll still have to use the standard text diff to see those.