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).
Instead, they plan to render the UI natively, with only "some" parts in HTML.
So, instead of XUL + HTML, we’re going to get GTK + WinForms + Cocoa + HTML. Great, eh?
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.
And the remaining addons can’t modify the UI (tree style tabs, bottom tabs, etc) anymore either, instead you can only modify page content.
I’m seriously pissed off now, because Firefox was the last browser where I could actually customize it how I liked it.
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.
Official statement from the Mozilla post in the discussion regarding removal of support for "heavyweight" themes. Emphasis mine.
That’s a pretty clear statement that it won’t be 100% HTML.
Also, the fact that "arbitrary styling and scripting" won’t be possible is another issue.
Tell me how I am supposed to write an addon that adds tab-previews as thumbnails when you hover over a tab like Vivaldi is doing it: http://i.imgur.com/vqysJs1.png ?
How am I supposed to write an addon that colors the navbar and the current tab in the theme color given by the HTML, or, if not existing, the favicon?
With current addons I can do that, with the new addon system, I’m seriously fucked.
The Palemoon developers understand the folly of ditching the flexibility of the XUL interface. They won't be removing it.
Lucky them.
So, a fork is a rough solution and will have maintenance issues for an app this size.
But these rants are just silly. XUL is a technology that needlessly duplicates what HTML/CSS do these days. And if you ever want to have a smooth transition to servo, which solves real, deep problems, having a html UI is going to be dramatically important.
I'm just really discouraged with how more and more desktop apps are being written in HTML, CSS and Javascript and suffer in quality as a result.
As long as Moore's law provides enough lift under our wings, RAM usage is one of the less important aspects of an application. However, I fear the trend of building application UI's in HTML/CSS because invariably it will lead to wildly inconsistent look, feel and behavior.
Sigh. I feel old.
Realistically, getting to feature parity after rewriting a core part of any application is going to be nearly impossible. You end up with different features, hopefully better ones, but not exactly the ones you had before you started. You can't step twice in the same river.
No one has listed the ten awesome features that we're going to get from HTML Firefox (cause there ain't many) or the 1,000 features (tons of little details) that will be lost. If users listed their 10 biggest problems with Firefox I doubt any of them would be solved by moving to HTML.
Imagine if instead of writing VSCode from scratch and releasing it alongside Visual Studio Microsoft had rewritten the Visual Studio UI in HTML, abandoned all the nonessential features, and abandoned the old native Visual Studio.
One might say that Mozilla will wait to release the new Firefox till it has all the old features of the old Firefox, but that's not been my experience with how teams work. They'll get frustrated with the rewrite and want to get it out the door. "We can add those features later" they will say, and then they'll never get added.