Mixed
wiki/html tables are not supported anymore. It was changed a long
time ago, look on the mailing list archives for the exact announce.
Not really, your exaple is working on Wikipedia :S
Then, even though your host has Tidy enabled, your wiki is probably not
aware of it (MediaWiki does a tidy pass, unrelated to automatic pass by
PHP).
You seem to be contradicting yourself. For clarification - are mixed
tables supported or not? I'm running 1.13 and have mixed tables working
fine last time I checked. Since wikitext table markup seems to
translate directly to HTML table markup, why would they not be compatible?
Mike