Categories: News

These Weeks in Firefox: Issue 92


  • Firefox will now update in the background for Windows Nightly users. See details in Bug 1703909 and this firefox-dev post.
    • We plan to stage roll out to Beta users in the Beta 89 cycle, and to Release users in the Firefox 89 cycle.
  • The Startup Skeleton UI has a new style and is set to ride the trains to release!
    • The skeleton UI, which shows an outline of the primary browser UI before Firefox has finished starting up, in dark mode.

      Firefox users on older or slower Windows machines will soon see this “skeleton UI” while Firefox is in the process of starting, rather than nothing at all.

  • Elastic overscroll (“rubberbanding”) is enabled on macOS (Bug 1704231).
  • Double-tap-to-zoom is enabled on macOS (Bug 674371). Double tap with two fingers to zoom in on a section of a webpage.
  • Thanks to our Outreachy candidates have been picking up good-first-bugs across Firefox!
    • There’s still time to apply – deadline is April 30th.
  • When viewing zip files, Firefox Profiler now automatically expands all the children.
    • The Firefox Profiler showing the contents of a compressed file. It has automatically expanded the folder structure to a profile file.

      This is especially handy if someone has compressed a whole bundle of profiles into a single file.

Friends of the Firefox team

For contributions from April 6 to April 20 2021, inclusive.


Resolved bugs (excluding employees)

Fixed more than one bug

  • Claudia Batista [:claubatista]
  • Dhanesh
  • Evgenia Kotovich
  • Falguni Islam
  • Garima Mazumdar
  • Itiel
  • kaira [:anshukaira]
  • Kajal Sah
  • Liz Krane
  • Luz De La Rosa
  • Manuel Carretero
  • Michael Kohler [:mkohler]
  • Michelle Goossens
  • msirringhaus
  • ryedu.09
  • Sarah Ukoha
  • Sebastian Zartner [:sebo]
  • Tim Nguyen :ntim

New contributors (🌟 = first patch)

Project Updates

Add-ons / Web Extensions

Addon Manager & about:addons
  • ntim fixed an alignment issue on the about:addons page options menu (regressed in the same nightly version by Bug 1699917, a proton related cleanup) – Bug 1703487
  • Michelle Goossens contributed a fix to ensure “Restart with addons disabled” opt-in the new Proton window-modal UI – Bug 1685346
WebExtensions Framework
  • Extensions web_accessible_resources are not blocked by CORS checks anymore – Bug 1694679
  • Fixed a bug that was preventing the “New Windows and Tabs URL” controlled by an extension to be updated as expected when the url changes as part of an extension update – Bug 1698619
    • NOTE: Firefox will re-prompt the user if the url is changed to an external URL from a previous one packaged into the extension itself

Developer Tools

  • Fission, targeting two upcoming milestones
    • M7a – working on BFCache related bugs
    • M8 – reaching feature parity with pre-Fission state
  • Style resources (*.css files) blocked by CSP are properly displayed in the Network monitor panel (bug).
    • The Network monitor developer tool panel showing blocked JavaScript and CSS requests due to CSP violations.

      It’s clearer now what got blocked due to CSP violations.

Installer & Updater

  • Of note to this audience: as part of this work,a  while ago we made launching devtools not apply updates: Bug 1120863.  We’d like to do more in that direction but It Is Complicated — cheers to :bytesized for the epic bug comment!

Lint and Docs

macOS Spotlight

macOS Spotlight is a new team spanning Desktop and Platform working on improving macOS platform integration. Come say hello to the team in the #macdev channel on Matrix! Here’s what the team has worked on since its inception in mid-February:

  • Native context menus are nearly done (Bug 34572). They’re currently disabled pending test failures (tracked in Bug 1700724). Enable widget.macos.native-context-menus to try them out.
  • When mousing to the top of the window in fullscreen, the title bar no longer covers the tab strip (Bug 738335).
  • Long tooltips will no longer appear on the wrong monitor (Bug 1689682).
  • The sidebar now has a vibrant see-through appearance (Bug 1594132).
  • Fixed an issue where the app menu would open at the wrong size then shrink (Bug 1687774).
  • Right click on the toolbar in fullscreen mode and click “Hide Toolbars” to hide the toolbar. This feature has been broken on macOS for years and is now fixed! This is useful for presentations (Bug 740148).
  • The Firefox System theme now changes with the “Auto” OS theme (bug 1593390).
  • Ongoing work on enabling native fullscreen by default (Bug 1631735). Enable full-screen-api.macos-native-full-screen to always use macOS native fullscreen.
  • Ongoing work on enhanced dark mode support. This includes theming the titlebar and non-browser windows like Library, using dark stoplight buttons, dark context menus, dark tooltips, dark highlight colors, and more. Enable widget.macos.respect-system-appearance to try it out (expect breakage!) (Bug 1623686).

Messaging System

Password Manager


  • OS.File is almost completely out of the startup path – only a handful of bugs remain and they all have patches up.
  • kmoir ported the “best practices for front-end Firefox engineers” document to source docs

Performance Tools

  • Made the profile info button more explicit
    • Before
      • In the Firefox Profiler UI, the button to get information about a profile is highlighted. It has a label "Uploaded Profile".


    • After
      • In the Firefox Profiler UI, the button to get information about a profile is highlighted. It has a label "Profile Info".


  • Marker tooltips now display the inner window ids if there are multiple pages with the same URL
    • The marker tooltip in the Firefox Profiler UI showing an "activate" DOM event. After the URL of the document that the event fired on, the string "(id: 25)" is shown.

      You can see the inner window ID at the right side of the URL now

  • Test category is being displayed first in the Marker Chart now, as they are very relevant when they exist

Search and Navigation

  • New address bar styling has been enabled!
    • fixes to colors, padding, icons and better support for custom themes (improved contrast, separators, hover/selected)
    • New tab page search hand-off to urlbar is moving to release with Firefox 89
    • Restyled the separate search bar
  • Fixed a bug where the default search engine couldn’t be changed under unexpected conditions – Bug 1693585
  • Removed support to install OpenSearch engines via FTP – Bug 1692018

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