Closed Bug 1431962 Opened 2 years ago Closed 2 years ago

OOP extensions do not properly display css


(WebExtensions :: Untriaged, defect)

57 Branch
Not set


(Not tracked)



(Reporter: pjohns33, Unassigned)


User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:59.0) Gecko/20100101 Firefox/59.0
Build ID: 20100101

Steps to reproduce:

This issue was reported to me by Windows users using my ShadowFox theme for Firefox [1].

* Download uBlock Origin

* Ensure extensions.webextensions.remote is set to true via about:config

* Utilize userContent.css to apply custom css for the webextension [2]


Actual results:

The entirety of the css is not used in the uBlock Origin popup [3 - Image 1].

* If you visit the relevant moz-extension url of the popup page in a new tab, all custom styling is seen. [3 - Image 2].

* If you set extensions.webextensions.remote to false, all custom styling is applied to the popup [3 - Image 3].


Expected results:

All styling should be seen in the webextension popup.

Additional comments:

* This problem has also been seen in uMatrix. 

* On a Mac, extensions.webextensions.remote is set to false by default.  I set it to true for testing and did not observe the same problem described here, indicating it is Windows specific and due to extensions.webextensions.remote.  Enabling this feature crippled the uMatrix popup, so I could not verify the issue there either.
Component: Untriaged → WebExtensions: Untriaged
Product: Firefox → Toolkit
Sorry. userContent.css is not officially supported.
Closed: 2 years ago
Resolution: --- → WONTFIX
This being labeled as WONTFIX on the basis of userContent.css not being officially supported is disappointing to say the least, particularly given that recent restrictions make userContent/Chrome the only way to customize much of Firefox. 

Is this indicative of an unwillingness to look into this particular problem, or Mozilla's new stance on userChrome/Content?  In other words, will the 40+ open bugs regarding these files be left untouched? Will the support for their implementation be un-maintained until they are completely unusable and yanked entirely from Firefox?
Not supported means that we will not actively support it, yes.

This isn't a new stance. These are undocumented features that happen to still work, but are no longer part of any official customization system. The functionality of userContent.css can mostly be duplicated using extension APIs. The functionality of userChrome.css will not be supported, for the same reasons that we removed support for legacy themes.

Support will probably be completely removed from Firefox in the future, yes, but there are no immediate plans to do so.
Thank you for the response, I really appreciate it. 

Some of the functionality of userContent.css can be replaced by extension APIs, but there are some major gaps that would be left: namely, the ability to alter FF's protected pages (AMO store, about pages, etc.) and customize extension popups.

I'm not sure I entirely understand the justification for removing their support, however, as (at least as far as I'm aware) they don't have most of the same compatibility, performance and security risks that legacy extensions posed.  Is this not the case?  Or are these features simply not a top priority and Mozilla doesn't have the workforce to maintain it? I think it would be a shame to have nearly all customization removed from FF, as it's one of my favorite aspects of the browser.  

I know you can't possibly give any form of official or certain answer, but do you have any guess as to when these features will be completely removed?  I guess I'm just trying to gauge how much more time I want to invest in creating custom themes via userChrome/Content if they won't be usable for long. I was planning on creating a similar repository to ShadowFox for Thunderbird, but I assume the same thing would apply there in terms of support.
I think this is a variant of bug 1394233 even though the condition is a bit different (bug 1394233 is about web pages with non-e10s, while this bug is about extention popups with remote-WebExtensions enabled). The problem disappeared when I disabled stylo.
I'd like to chime in here. Quantum was a huge step forward and catapulted Firefox right back to the top of best browsers. It's fully understandable that in the interest of stability and security, you guys had to drain the add-ons swamp and clean it all up with tight APIs etc..

Power users like myself hated that at first, but the most important add-ons were quickly migrated, thanks to the awesome authors that make them. Thanks a lot here and now to all of them.

Plus, there were promising voices e.g. from the Tridactyl crowd that they were working with the FF devs to address limitations, such as why we shouldn't be allowed to use Tridactyl on pages like, or be unable to open pages like about:config.

Finally, there exists userChrome.css, which I use for instance to hide elements of the UI that I plainly don't need (such as the navbar, which no longer can be dragged off the toolbar), or move things around so that I can make Firefox my own, and make it fit my mode of work.

Now, if you're telling us — and that's basically how I have to read the above comments — that you care not a little bit about userChrome.css, I have to assume that it'll be gone any day now. And I further have to assume that the Tridactyl crowd, and probably many others that are trying to make your browser awesome within the constraints you set, are going to find out that you don't care about them either.

So really, why should I bother to invest any more time with Firefox? Chromium is faster, and equally limited as what you're apparently striving for.

Please don't actively push away your power users, or you'll lose the entire marketing brigade that we are. Because currently, I feel good telling people to use Firefox as their browser, because it's made by a company/community that cares about its users, rather than part of some corporate agenda. Please don't work hard to convince me that this is no longer the case.

— a Firefox power user, since Mosaic, basically.
Product: Toolkit → WebExtensions
You need to log in before you can comment on or make changes to this bug.