[dmm]

> Mozilla's response to that was "Go fuck yourselves."

Do you have a source for that or are you just making things up?

My observation was that Mozilla consistently responded to complaints from extension authors by implemented new apis for their webextension implementation to allow extensions to be ported. That's pretty far away from "Go Fuck Yourselves."

> Mozilla introduced many new WebExtensions APIs in Firefox 57 [Quantum], such as the openerTabId property for tabs. The opener information is highly relevant for Tree Style Tab. [0]

[0] https://hacks.mozilla.org/2017/12/webextension-tree-style-ta...

[Causality1]

Then why can extensions still not customize the UI, even for something as simple as putting the tabs below the address and bookmarks bar?

[dralley]

That's what UserChrome.css is for.

[DiabloD3]

I don't know why this guy was downvoted, he's correct.

I even have a pretty decent UserChrome.css to better integrate Tree Style Tab, https://www.reddit.com/r/FirefoxCSS/comments/ao3ydl/configur...

[Causality1]

Which is handy but not relevant to my question of "why can't an extension do this" with the implied "so I don't have to fiddle with copy-pasting text off the internet into configuration files I'm not entirely familiar with using." Not to mention that by default Firefox 69 disables loading of userchrome.css and you can bet your britches they're doing that in future anticipation of removing the feature entirely just like they did with everything else they've stripped out.

[darkpuma]

Because it's trash UX to ask users to find and modify their userchrome.css when they should be able to simply install the extension and have it work.