Env: Firefox 3 (nightly build 20061218) Problem: You cannot navigate the tree view using the arrow keys including left/right to collapse/expand. The twistie are not drawn correctly, they show up as " ". Double clicking with the mouse should toggle expansion, this also does not work. Steps to recreate: 1. Start WindowEyes and Firefox, load url: http://www.mozilla.org/access/dhtml/tree 2. Try navigating with arrow keys, or left right arrow to collapse/expand, you will notice that you cannot perform these tasks. NOTE: This is a regression since it works fine with Firefox 2.

Firefox 2 thinks the file is application/xml+xhtml, which is correct -- that's how Apache is serving it. Firefox 3 thinks it is text/html -- why is that?

Smaller test case where file is getting parsed as html instead of XHTML: http://www.mozilla.org/access/dhtml/maincontent

Is this related to bug 361892?

This was caused by bug 309438.

Doesn't that mean that this is a server-side configuration issue?

Maybe, but why we make everyone fix their servers when they've been following published docs on how to configure. It used to work and now it doesn't. Everyone who's done this will have a painful discovery process when it breaks in FF3. What's the payoff for the change we've made?

The payoff is that our XHTML support is a LOT worse than our HTML support (e.g. no incremental rendering in XHTML). If the site thinks that its XHTML and HTML are equivalently good, we should be using the HTML version. What published docs is comment 7 referring to? I suspect the docs were rather erroneous to start with... (e.g. suggested that the server configure XHTML and HTML with identical priority when you actually prefer the XHTML).

Thanks this works: RewriteCond %{HTTP_ACCEPT} !application/xhtml\+xml\s*;\s*q\s*=\s*0(\.0{1,3})?\s*(,|$)