Unfortunately, any mention of creating a lean UI based on HTML5 creates a huge debate, nee a holy war, in the Firefox community because this is deemed to reduce the ability to extend the Firefox UI through extensions. Please refer to [1] for a protracted argument on why WebExtensions (or similar framework) are a step-back&#x2F;inferior because they don&#x27;t allow for extending the Firefox UI the way XUL-based extensions do. There are a number of power-users and vocal community members who believe that Firefox must have XUL-based extensions otherwise it becomes an inferior clone of Chrome (bollocks if you ask me).<p>[1] <a href="http:&#x2F;&#x2F;forums.mozillazine.org&#x2F;viewtopic.php?f=23&amp;t=2956625" rel="nofollow">http:&#x2F;&#x2F;forums.mozillazine.org&#x2F;viewtopic.php?f=23&amp;t=2956625</a>