But, sadly, they aren’t replacing XUL with HTML.<p>Instead, they plan to render the UI natively, with only &quot;some&quot; parts in HTML.<p>So, instead of XUL + HTML, we’re going to get GTK + WinForms + Cocoa + HTML. Great, eh?<p>And we lose the ability to style it with addons – your themes can only change the background image of the header bar, that’s it.<p>And the remaining addons can’t modify the UI (tree style tabs, bottom tabs, etc) anymore either, instead you can only modify page content.<p>I’m seriously pissed off now, because Firefox was the last browser where I could actually customize it how I liked it.<p>I hope the person who made this decision is going to have to use software without any config options and with horrible defaults, like GNOME. For the rest of their life. May their car always have have either 60°C+ heat, or -20°C AC, may their screen of their phone always either be too dark, or too bright.