Categories: News

These Weeks in Firefox: Issue 96


  • Improved dark mode support for macOS is now enabled in Nightly and Early Beta! When Firefox is in dark mode, look out for:
    • Dark Library/Page Info windows
      • The Library window on macOS, styled with the Dark Theme

        This is what the Library looks like with the lights off.

    • Dark tooltips
      • The Firefox tab strip with the mouse hovered over one tab. A dark tooltip says "Firefox Privacy Notice - Mozilla (pid 6752)"

        Dark tooltips, too!

    • Dark text selection colors in UI chrome
    • Dark autocomplete popups (login autofill, etc)
      • The autocomplete dropdown is shown below a form input. The dropdown is dark themed, and suggests the string "Mozilla" for a "Company" form field.

        These autocomplete dropdowns are getting dark, too!

    • Dark window styling, including dark stoplight buttons and the elimination of the dreaded white line at the top of dark windows
    • If you notice things that don’t look right, please file bugs blocking Bug 1623686.
  • Dimi landed password manager support for multi-page login forms! The password manager will now:
    • Detect username only forms
    • Support autofill, autocomplete, and context menu in these username only forms
    • Support login capture when users submit the multi-page form with the password

Friends of the Firefox team

For contributions from June 1 to June 15 2021, inclusive.


Resolved bugs (excluding employees)

For contributions from June 1 to June 15  2021, inclusive.

Fixed more than one bug

  • Andrey Bienkowski
  • Ava Katushka
  • jha.ashray12
  • Kajal Sah
  • Michelle Goossens

New contributors (🌟 = first patch)

Project Updates

Add-ons / Web Extensions

  • Sonia Singla contributed a patch to remove the about:config preference “extensions.allowPrivateBrowsingByDefault” (it has been introduced as a fallback mechanism to return to the older behavior, during the transition to the user-controlled extension permission to selectively allow extensions to run in private windows) – Bug 1661517
  • As part of the work to support “Manifest Version 3 extensions”, an initial chunk of the work to expose the WebExtensions APIs to the extensions’ “background service worker” has been landed in Nightly 91 (locked behind a pref that can only be enabled in Nightly builds) – Bug 1682632
    • Bug 1682632 does not expose yet any actual extensions APIs to the background service workers, an initial set of APIs (browser.alarms, browser.runtime and browser.tests) are part of the follow up Bug 1688040
    • For an high level view of the plans related to “Manifest Version 3 extensions” support, follows the blogpost we recently published on the “Mozilla Add-ons Blog”:

Downloads Panel

  • Outreachy intern, Ava, has landed the following:
    • A change where downloads opened with a computer application through the “What should Firefox do with this file?” prompt are directly saved to the Downloads folder (bug 1710933). This was already the behavior on macOS, and now Windows and Linux do this too if the preference is set to true.
    • Test for basic functionality of downloads telemetry (bug 1712997)
  • In-progress:
    • Ava is working on making “Save to disk” the default decision for downloading files (bug 171094). She’s already written a patch. This change is also behind the
    • Ava has started investigating how frequently we should be opening the downloads panel (perhaps with an option to opt-out?) (bug 1709129)

macOS Spotlight

  • Work continues on native fullscreen support.
  • Work continues on reducing power consumption during video playback.
  • We’re looking into reports that Firefox is triggering memory pressure warnings, especially on M1 Macs.

New Tab Page

  • Upcoming (Firefox 90) Private Browsing New Tab Page experiment to promote Mozilla VPN with 3 different design variations bug 1715504

Nimbus / Experiments

  • Working on a wrapper API to allow cpp/platform clients to use the Nimbus API bug 1716560


  • In-tree Node 10 -> Node 12 upgrade expected to land today (Tuesday, June 15th)
    • This mailing list post has more details
    • Most developers shouldn’t need to do anything.
    • A followup post will be sent after the landing with details for the few folks who may wish to verify that everything is still working for them.

Password Manager

  • Tgiles landed an improved password generation experience by utilizing Apple’s password rules data! Bug 1686071
    • Now when users generate passwords on sites that have an entry in the “password-rules” dataset, we will generate a stronger and more accurate password based on site requirements!
    • Note: we currently do not have Apple’s password rules data pulled into Firefox so the improved password generation experience is not noticeable yet. The data should be pulled in within the next week or two.


  • Hang stats! Did you just add new code that runs on the main thread? Our BHR (Background Hang Reporter) system can help you detect if it’s causing hangs for our users in the wild. You can view the latest hang data here!
  • mconley landed patches to make it possible to control the about:home startup cache via Nimbus
    • The goal is to do a Nimbus experiment to see how the cache impacts user behaviour on Beta and (maybe) Release

Performance Tools

  • Screenshots are now visible while selecting a time range.
    • The Firefox Profiler UI shown in an animated GIF. The animation shows the cursor selecting a time range, and a smaller version of the collected screenshot for the slice of time being hovered is shown.

      One of our most powerful performance tools just got a bit better!

  • Profiler rust API for thread registration has been landed now. If you are working on a Rust project with multiple threads, don’t forget to register your threads with the Gecko Profiler. It’s pretty straightforward with gecko_profiler::register_thread and gecko_profiler::unregister_thread endpoints. More Rust API endpoints for the profiler coming soon!



Search and Navigation

  • Harry fixed a problem with a synced preference causing some address bar results to not appear anymore – Bug 1715484
  • Harry is doing some re-architecture work to split the old unified address bar provider into separate providers, that will give us better separation of concerns and control over results composition – Bug 1677126, Bug 1662167, Bug 1712352
  • Harry reduced the padding around search shortcut buttons in the address bar – Bug 1712775
  • Daisuke corrected cut text glyphs on address bar results – Bug 1565448
  • Daisuke fixed a problem with the focus ring briefly appearing on the address bar when clicking its border – Bug 1708263
  • Daisuke converted the separate search bar shortcut buttons to compact mode, like in the address bar – Bug 1709405
  • Drew is working on improvements to address bar results flexibility – Bug 1713322


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