SeaMonkey has a Debug > XUL Test Suite submenu. In SM 2.7b2 and b3, every item on that menu results in XML parsing errors. Visiting same URLs in Firefox nightly results in the same errors, so I'm filing a core bug. Steps to reproduce 1. Choose anything from SeaMonkey's Debug > XUL Test Suite menu, or enter a URL like http://www.mozilla.org/projects/xul/tests/stacks.xul Results: XML Parsing Error: Location: http://www-archive.mozilla.org/projects/xul/tests/stacks.xul Line Number 28, Column 37: onload="" orient="vertical"> ------------------------------------^ But the document passes XML validation ( http://validator.w3.org/check?uri=http%3A%2F%2Fwww.mozilla.org%2Fprojects%2Fxul%2Ftests%2Fstacks.xul ), so it's something else. On IRC NeilAway commented "probably remote xul blocking it". If I save the file locally as test.xml I get the same parsing error, but if I change the extension to .xul I get an in-window rounded box error Remote XUL This page uses an unsupported technology that is no longer available by default. So maybe there's a bug separate from the test suite that a Remote XUL error is misreported as an XML Parsing Error. And a wish that the Remote XUL Manager add-on https://addons.mozilla.org/en-US/seamonkey/addon/remote-xul-manager/ be compatible with SeaMonkey 2.7.
XUL elements in a non-XUL remote (and that includes file:// URIs) page are treated as a parse error, last I checked. I believe that's the expected behavior, but ccing sicking to confirm.
Yup, this is expected behavior since we disabled remote XUL. If you load XUL using chrome:// urls it should work just fine, but you can probably not load these test pages that way without installing them as an addon.
Wow, working 7 days a week, thanks! I filed bug 718356 to remove the submenu in SeaMonkey. The XML Parsing Error is unhelpful and points to a random part of the XUL file, but I'll let it go ;-)