&gt; The reasons given, that XUL requires maintenance that Mozilla engineers don&#x27;t enjoy doing, is a joke considering the amount of effort to maintain XUL is less than 1% of the amount of effort to move Firefox to HTML.<p>Ah, but maintaining XUL means working on old code (which is boring), but moving Firefox to HTML means working on new shiny code (which is exciting).<p><a href="https:&#x2F;&#x2F;www.jwz.org&#x2F;doc&#x2F;cadt.html" rel="nofollow">https:&#x2F;&#x2F;www.jwz.org&#x2F;doc&#x2F;cadt.html</a>