Hello,
Last I heard, many Wikimedia and other MediaWiki installations relied on HTML Tidy to some degree to cope with bad markup, like templates may generate. There is also some interest in using "HTML5" features in MediaWiki wikis, but combining the two is difficult as Tidy will choke on elements it does not know (since it does not know how to parse them) and configuring them with the new-*-tags options is troublesome.
I made http://lists.w3.org/Archives/Public/www-archive/2011Nov/0006.html some patches to address that problem (and only that problem really, Tidy is not going to be a proper "HTML5" parser that parses documents exactly as a browser would) so that Tidy keeps working with old markup as usual, but doesn't choke on new elements, doesn't complain about new attributes and doesn't "break" conforming documents. Where new markup is malformed, Tidy is unlikely to repair it as sensibly as it does for old markup, and it may in fact make them even more malformed or otherwise break them. I do not care about that at this point, and there is nobody else contribu- ting code to the project of late.
I am interested in polishing my patch and including this in the official repository, but I need people I can blame instead of myself when it does not work right, err, I mean, testers. I haven't heard from anyone with a MediaWiki background that they actually had some problem with Tidy plus "HTML5", but if that is just because deployment is slow, this is likely the best place to look for takers.
Discussion is taking place on tidy-develop@lists.sourceforge.net but you can also use the bug tracker on sourceforge or mail me directly, ideally sending a copy to www-archive@w3.org so there is a publically archived copy I can refer others to if they would like to help out. Feedback on other things than the patch or "HTML5" support in general is welcome too of course.
regards,