>>35Well, notwithstanding, Mozilla decided to call 57 Quantum to mark the first release that introduced Servo components, namely Stylo aka Quantum CSS. What's more significant about this release, however, isn't so much the immediate features it's introduced but rather the direction it represents, in which future Firefox versions will include more and more Servo components until possibly complete assimilation with Servo.
Now, let's look at what Firefox replaced, XUL, and some of the technical differences that are affecting us in the here and now:
• XUL extensions have the same amount of control over your OS as Firefox does, so they can download and execute scripts, modify in, say, ~/, ~/Documents/Taxes, etc.
• there is no way to limit an extension's permissions or sandbox it. XUL extensions makes it harder to implement multithread, which is in turn inefficient and a security threat if (by which I mean inevitably) implemented improperly
• XUL extensions depend on Gecko, so any update to the browser may render them unusable, guaranteeing that every (or most) extension can potentially break with an update, and reviewing every add-on uploaded to the addon store is too taxing for Mozilla (which is why the don't)
• WebExtensions have thousands of developers and are applicable to the vast majority of Firefox addons, so the change and extension fallout is far less severe than you make it out to be, most cases only affecting addons that have already been forsaken by their creator
• popular addons that cannot be ported to WebExtensions have been (or are planned to be) an inherent feature of the browser (like TreeStyleTabs)
• Mozilla is developing new APIs to give developers access to some of the same functions XUL allowed, making the ``less api's, less functionality'' argument no more than a bump in the road