Firefox Quantum compatible userChrome.js
What does this do?
It does not involve adding any extensions, and instead works only by adding (or changing) files in your Firefox user profile.
After I made this I learned of something called
autoconfig.js which apparently serves a similar purpose; I haven't investigated it very much.
Place the three
userChrome.* files in a
/chrome directory inside your Firefox profile. If you already have a
userChrome.css file, you may instead add the contents of the file here anywhere in your existing file.
Replace the contents of
userChrome.js with whatever you wish; it will execute in the browser context whenever you open a new browser window. The existing contents of that script (in this repo) are a small change to the fullscreen behavior of Firefox under macOS: it restores the pre-Lion behavior (and hides the toolbar and tabs when in fullscreen mode).
You may also place
.css files in the
/chrome directory, these will be loaded along with
.uc.xulfiles are XUL overlays that will load into the browser.
.cssfiles will loaded as USER_SHEETs into all pages, including the ui (chrome:// urls), a sort of userChrome/userContent hybrid. Use
@-moz-documentrules to limit them to certain pages. (userChrome.css and userContent.css will behave as normal).
- A special case,
.as.cssfiles, are loaded as AGENT_SHEETs, allowing you to style anonymous content like scrollbars.
To uninstall, remove the three files. If you have other content in the
userChrome.css file you can remove just the part that you added during installation.
Why did I make it?
I wanted to enable pre-Lion osx fullscreen mode, and couldn't find an easy way to do it in Firefox Quantum. It's possible with unpacking, altering, and repacking files in the
How does it work?
It relies on the fact that post-57 Firefox still allows a custom
It's very possible that at some future time the Firefox team will remove some or all of the functionality that makes this possible, so enjoy it while you can.