Found the problem, and here is the working code in full: https://gist.github.com/Zegnat/c5d4247dd7aa955dc9f1
You had to use `controls="controls"`. DOMTemplate will change this to just `controls` when it outputs HTML, but the code you are using is a bit of a hack I made that works only on XML. Attributes without value aren’t allowed in XML. I guess “Invalid XHTML” would have been a better Exception to throw, as your HTML was completely valid.
I have also opened up an issue on the bug tracker regarding the sitemap: https://github.com/Kroc/NoNonsenseForum/issues/191. Haven’t had the time to look for a solution yet.
Hope this helps!