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Release Notes tell you what’s new in Firefox. As always, we welcome your feedback. You can also file a bug in Bugzilla or see the system requirements of this release.

Firefox Developer Edition — English (US)

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Firefox Developer Edition — English (US)

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Firefox Developer Edition

August 14, 2015

Version 42.0a2, first offered to Firefox Developer Edition channel users on August 14, 2015


  • Improved private browsing windows block some web page elements that could track your web behavior across sites

  • Control Center that contains site security and privacy controls

  • Indicator added to tabs that play audio with one-click muting

  • GTK3 integration (GNU/Linux only)

  • Hardware acceleration for 2D canvas content (Mac OS X only)

  • Process separation enabled by default in Developer Edition

  • Login Manager improvements:

    • Improved heuristics to save usernames and passwords
    • Edit and show all logins in line, Copy/Paste usernames/passwords from the Context menu
    • Migration imports your passwords to Firefox from Google Chrome for Windows and Internet Explorer; import anytime from the Login Manager
  • WebRTC improvements:

    • IPV6 support
    • Preferences for controlling ICE candidate generation and IP exposure
    • Hooks for extensions to allow/deny createOffer/Answer
    • Improved ability for applications to monitor and control which devices are used in getUserMedia


  • Improved performance on interactive websites that trigger a lot of restyles


Developer Information

Web Platform


  • The CTRL+K shortcut does not give focus to the search field when used from the URL bar on GNU/Linux with GTK+ 3.14 and 3.16 (1176929)