The Screenshots feature in Firefox functioning within the about:config page
Categories: News

A Better Screenshots Tool and More – These Weeks in Firefox: Issue 156


  • The new Screenshots component (which replaces the Screenshots built-in extension) is now enabled by default on Nightly (bug 1789727)! This improves upon the extension version of the feature in a number of ways:
    • You can capture screenshots of about: pages and other pages that extensions cannot normally manipulate

The Screenshots feature in Firefox functioning within the about:config page

    • Improved performance!
    • Greatly improved keyboard and visual accessibility
    • You can ensure it’s on by default by checking if screenshots.browser.component.enabled is set to true in about:config
    • Found issues with the new component? File them here!
    • You can access the Screenshot feature via the keyboard shortcut (ctrl + shift + s or cmd + shift + s for macos), the context menu, or by adding the Screenshot button to your toolbar via toolbar customization
  • The Firefox Profiler has a new “Network Bandwidth” feature to record the network bandwidth used between every profiler sample. Example profile
  • Two different timelines - one for Network and one for Bandwidth - in Firefox Profiler.
  • Florian gave a FOSDEM talk about the Firefox power profiling
  • Nicolas added support for incoming input[type=range]::slider-* pseudo elements (bug)
    • behind layout.css.modern-range-pseudos.enabled

The devTools inspector showing CSS rules for several input slider pseudo elements

The Firefox address bar with a "Visit from clipboard" button

Friends of the Firefox team

Resolved bugs (excluding employees)

Script to find new contributors from bug list

Volunteers that fixed more than one bug

  • Bojidar Marinov [:bojidar-bg]
  • Nikki Bernobic [:echrs]

New contributors (🌟 = first patch)

Project Updates

Developer Tools

  • Arai fixed an issue where ReadableStream.values() was eagerly evaluated  (bug)
  • Alex added a button dedicated to source map settings in the editor footer (bug)

Tooltip at the bottom of the devTools editor displaying available Source Map settings and which of those settings are enabled.

  • By popular demand, Alex added back the preference to control the Debugger Pause Overlay (bug)
    • set  devtools.debugger.features.overlay to false if you want to disable it
  • Alex fixed performance issues in the debugger when a page had a lot of sources (bug)
  • Hubert fixed an issue in the debugger where the Outline view wouldn’t populate (bug)
  • Julian fixed opening relative URL of <img> on pages with a <base> (MDN) tag (bug)
  • Alex added an option in the tracer to track all DOM Mutations (bug)
  • from the console :trace –dom-mutations
  • (Set devtools.debugger.features.javascript-tracing to true to enable the tracer)

The Tracer in Firefox devTools notifying when and at what time a DOM mutation occurs

WebDriver BiDi
  • Thanks to Kagami who implemented set_permission for marionette driver (bug)
  • Sasha implemented the storage.deleteCookies command for WebDriver BiDi. (bug)
  • Sasha added support for the userContext field of the partition parameter for storage.getCookie and storage.setCookie commands. (bug)
  • Julian implemented a basic version of the network.provideResponse command. (bug)

ESMification status

  • ESMified status:
    • browser: 100%
    • toolkit: 99.83%
    • devtools: 89.29%
    • dom: 96%
    • services: 98.94%
    • Only 10 JSMs left in the tree!
    • Total:  99.35% (+0.00% from last time)
  • #esmification on Matrix

Lint, Docs and Workflow

Migration Improvements

New Tab Page

  • We’re in the early phases of building out an experiment that lets people set wallpapers on about:home/about:newtab. Stay tuned!

Performance Tools (aka Firefox Profiler)

  • Made the call tree sidebar localizable.

Call tree sidebar in Firefox Profiler displaying various characters and letters to demonstrate that it can be localized into different languages.

  • Marker count is shown next to the marker name in the marker chart when a marker is hovered.

A table in Firefox Profiler showing DOMEvent as a listed event that was counted up to 410 times.

  • Improved performance of the marker chart when there are so many overlapping markers.
  • Improved the power graph and made it easier to see very small values in the graph by hiding the zero values.

  • Before:

The power graph in Firefox Profiler before implementing changes that make it easier to see small values

  • After:

The power graph in Firefox Profiler after implementing changes that make it easier to see small values

  • Fixed the hittesting on the activity graph.

Activity graph for a sample Firefox Profiler profile that ran for 686ms.

  • Fixed the marker stacks that were broken because of a symbolication issue.


Search and Navigation

Storybook/Reusable Components

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