&gt; <i>Being nonstandard is completely irrelevant here</i><p>It was meant as a pro. Since it was their own language, they could do anything with it. They could make a better HTML.<p>But HTML caught up. Currently, I believe HTML is better than XUL, and making XUL great again is both a silly reuse of a political slogan and a waste of effort.<p>I for one would rather see efforts made to allow CSS styling of all input elements in HTML.