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Today’s meeting leader is: mconley

General Topics / Roundtable


Friends of the Firefox team


  • New interns!

    • Mandy Cheang (@mcheang, mandy__)

      • Working on improving start-up performance
    • Abdoulaye Ly (@Abdoulaye O. Ly, abdoulaye)

      • Working on Fission

Resolved bugs (excluding employees)

Fixed more than one bug

  • Florens Verschelde :fvsch
  • Ian Moody [:Kwan]
  • jaril
  • Kestrel
  • Monika Maheshwari [:MonikaMaheshwari]
  • Tim Nguyen :ntim

New contributors (🌟 = first patch)

Project Updates

Activity Stream

  • The new Pocket Newtab is on track for 68 with performance parity

    • Slight regression with our usage of -webkit-line-clamp (thanks heycam for platform implementation!) and fixing with requestAnimationFrame (thanks performance best practices doc)

  • We’ve made some progress on migrating our build process into Firefox / making it easier to develop on Activity Stream features

  • Introducing our new intern: Emily (:emcminn)!

Add-ons / Web Extensions



  • No updates this week.


  • Work on the Lockwise addon is complete

    • Final release waiting on localizers to translate strings

  • Future Lockwise work will happen in tree as part of Password Manager
  • Removing this Lockwise item after this meeting

Firefox Accounts

Sync and Storage


Browser Architecture

Developer Tools

Layout Tools

  • Inactive CSS landed! It's currently only ON by default in nightly (since 68) but will ship to everyone with Firefox 69. Bug 1306054.

We will be adding a larger collection of warnings very soon too, to warn users about more tricky CSS cases.

(link:, alt: tooltip shown on css properties that have no effect on the current element in the inspector. This one shows a justify-content property on a non-flex element).

  • Expandable CSS warnings also landed (shipping with 68).

This allows jumping directly from a CSS warning displayed in the console to a node in the inspector when the warning occurred inside a CSS rule. Bug 1093953.

(link:, alt: CSS warnings in the web console, with one of them being expanded, and revealing a list of DOM nodes that the warning applies to).

  • CSS Grid level 2 (subgrid) is close to shipping in Firefox. We're getting the tooling for it ready in Firefox 69 so it's easy to see the relationship between a grid and a subgrid.
  • We're continuing to prototype on WebCompat awareness tools. Our latest prototype is an addon that displays CSS compatibility information about a page from the Firefox toolbar. It now allows to jump from a warning into the Style Editor, and to open other browsers where issues occur. GitHub repo for the addon


(link:, alt: GIF demonstrating the doorhanger menu added by this extension, which contains the list of CSS compat problems detected on the page).

  • We're also focusing on fixing the last few remaining issues preventing to support the <meta viewport> tag in RDM, and therefore simulate mobile devices better.
  • The color-picker just got a bit of a re-design. Bug 1478152. Thanks Maliha Islam [:maliha] for pushing this over the edge.


(link:, alt: The new color-picker in the inspector panel).


  • We now have borders between messages to make them easier to read. Bug 1519904. Thanks Florens Verschelde :fvsch for your keen eye for details.


(link:, alt: Screenshot of the console in firefox 68 with borders between each console log message).

  • It is possible to resend network requests that were logged in the console. Bug 1530138. Thank you Christoph Walcher.

(link:, alt: screenshot of the context menu in the web console, showing the new "resend request" feature for network requests).


  • Column breakpoints are stable now and we’re super happy with it.
  • Event breakpoints making good progress. The UI is ready and we'll be landing the feature very soon. Bug 1526082.


(link:, alt: a preview of the soon to come event breakpoints panel in the debugger, allowing you to set breakpoints on all event types).

  • Workers are now displayed in the source tree along all the other sources.


(link:, alt: the source tree in the debugger, now showing all workers, alongside normal sources).

  • The new logpoint feature is now even better with dedicated icons in the web console.


(link:, alt: the new "add log" menu item in the debugger context menu, allowing you to log an expression when a certain line of code is executed).

Remote Debugging

  • The new about:debugging page will ride the trains with Firefox 69. A final QA testing phase will happen in beta 69 in a few weeks. The main implementation phase is over and the final few fixes have happened:

    • Stay on the same page when reloading about:debugging (reconnects to remote runtimes automatically) (bug)

    • Remember last temporary addon install directory (bug)

    • Disable temporary addon installation if xpinstall.enabled is false (bug)

    • Updated error message colors and borders

    • New "Remote Debugging" menu item in the Web Developer menu

    • Update for Fenix/Firefox Preview (name, icon and version) (bug)


  • Abdoulaye has an initial version of the <select> dropdown working with Fission
  • Neil has a version of drag and drop working with Fission! \o/
  • mconley has a patch that makes PermitUnload work with Fission, but is blocked on some DOM work
  • mconley is starting efforts to make the context menu work with Fission


Password Manager


Performance tools

  • Properly updating the URL state after publishing now.
  • Improved algorithm to find idle threads at load time.
  • Firefox Profiler now supports SimplePerf output format.
  • Added more relevant information to window title to improve the searchability of tabs. Thanks to our GSoC student Raj!602x74px

Title of Firefox Profiler tab

  • Transforms are usable inside stack chart via context menu now.


New context menu inside stack chart tab


  • Dave Justice is about to get a patch landed that decorates the tab that a Picture-in-Picture video is coming from
  • Keyboard access and RTL support for Picture-in-Picture is still underway
  • The tentative plan is to let this ship to Beta / Dev Edition and get feedback from our users and web developers

Policy Engine

  • ExtensionSettings policy finally landed (bug 1522823)
  • Added a number of preferences to the new Preferences policy (bug 1545539)
  • Download related policies (bug 1546973)
  • Activity Stream policies (bug 1548080)
  • Legacy Browser Support

    • EXE built

    • Able to test extension

    • Working on IE BHO

  • Investigating multiple intermittents on policy that have been around a while (Any advice?)


Search and Navigation


Quantum Bar:

  • Bugs and cleanup work
  • Active in Beta, no critical regressions reported so far
  • Nightly XUL/Html experiment didn’t show any fallbacks
  • Adding core support for the WebExtension APIs that will be driving our future experiments

User Experience

This week I learned

  • [jaws] `composed: true` with shadow DOM
  • [jaws] script type=module can now be used from privileged about pages
  • [MattN] `./mach mozregression` exists, no need to `pip install` yourself
  • [MattN] How to check from the parent which principal a subframe has loaded in a Fission-compatible way

    • Content: Get `` from the subframe and send that along with your message to the parent

    • Parent: `BrowsingContext.get(`