Categories: News

These Weeks In Firefox: Issue 119


  • Allow the browser toolbox to enable/disable multiprocess behavior on-demand (bug). The user can switch between two modes.
    • Parent process only (fast) – observing only the parent process and useful for debugging Firefox UI only
    • Multiprocess (slower) – observing all chrome as well as content processes

  • The Firefox Profiler can now sort roots in alphabetical order with a flamgraph. This is especially useful when comparing profiles with the JavaScript filter, as this ensures that the order is consistent.

  • Add tracks for power usage (this works on MacOS M1 and Windows 11 especially)

Follow along bug 1774844 to know when the feature will land to Firefox.

  • Subtitles setting panel is now in Firefox 103. Make sure `media.videocontrols.picture-in-picture.display-text-tracks.enabled` is set to true in about:config and subtitles are enabled on the original video.


Friends of the Firefox team

Resolved bugs (excluding employees)

Volunteers that fixed more than one bug

  • Itiel
  • Mike Ratcliffe [:miker] [:mratcliffe] [:mikeratcliffe]
  • Rob Lemley [:rjl]
  • Zoltán Szatmáry

New contributors (🌟 = first patch)

Project Updates

Add-ons / Web Extensions

(read-only due to overlapping with our team’s remote workweek meeting)


Addon Manager & about:addons

  • InstallTrigger Deprecation: Bug 1772905 landed in Nightly 103 as mentioned two weeks ago: the InstallTrigger global is now fully hidden on nightly and early beta.
    • NOTE: Please link to Bug 1774005 bug reports of website breaking due to websites using InstallTrigger for UserAgent detection (e.g. see Bug 1773873) if you notice newly filed ones during “Firefox :: General” triaging

WebExtensions Framework

  •  As part of the ongoing ManifestVersion 3 (MV3) work:
    • Added to the browserAction (the toolbar extension button) context menu new entries to allow the user to grant/revoke permissions for the current website (currently restricted to MV3 extensions) – Bug 1769793
    • For MV3 extensions, all host permissions are considered optional and not granted (until the user has explicitly granted some to the extension). When the user activates the browserAction button (e.g. by clicking on it), the extension content scripts will be temporarily allowed to be injected in all same-origin frames of the current tab top-level origin if the top-level origin matches at least one of the host permissions listed in the manifest – Bug 1774641

Developer Tools

Browser Toolbox

  • Performance improvements for Browser Toolbox Debugger
    • Source tree in the Debugger panel (bug)
    • Code editor CodeMirror (bug)
    • Reduce number of state updates (bug, bug, bug)


  • Performance improvement for Browser Toolbox Console
    • Avoiding cloning Map() objects (bug)


  • Mike Ratcliffe is making lots of contribution to DevTools these days and fixed an issue where we would limit the number of indexedDB items you could see in the storage panel (bug)
  • Thanks to arai we now display getter/setter in arrays (bug)


WebDriver BiDi


Performance Tools (aka Firefox Profiler)

  • Huge documentation improvement. (along with the removal of the documentation of the old panel)
  • The tooltip for markers is now showing the originating thread when we’re in the view for merged tracks.
    Reminder: you can merge tracks by ctrl clicking their names in the timeline (the top part).

  • Local threads are alphabetically sorted at load time, which is nice for threadpools especially, when you’re looking for a specific track in the list.
  • We now have smaller URLs by default, which should avoid the problem where a permalink couldn’t be created with profiles that have a lot of tracks
  • New locale: frisian (fy-NL) (locale with more than 400k speakers, originating in netherlands).
  • As an aside Gerald worked on reducing the timer thread wake-ups to reduce the power usage for this thread.


  • Eval has been disallowed in the parent process and system privilege context for some time, but as part of Pwn2Own followup investigation we discovered it was not properly being blocked in .jsm files. After the merge we will be landing this enforcement – if you encounter breakage please cc Tom Ritter on the bug. You can work around it by disabling the prefs.


Search and Navigation


ESMification status

  • Most of the preparation work has been completed.
  • Documentation and scripts for semi-automatic migration are undergoing testing.
  • Hoping to open up to teams next week.

No comments yet

Post a comment

Leave a Reply

Your email address will not be published. Required fields are marked *