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Firefox Notes (First offered to release channel users on May 14, 2013)

Check out "What’s New" and "Known Issues" for this version of Firefox below. As always, you’re encouraged to tell us what you think, or file a bug in Bugzilla.We'd also like extend a special thank you to all of the new Mozillians who contributed to Firefox 21!

If interested, please see the complete list of changes in this release.

What’s New

  • NEW
    The Social API now supports multiple providers
  • NEW
    Enhanced three-state UI for Do Not Track (DNT)
  • NEW
    Firefox will suggest how to improve your application startup time if needed
  • NEW
    Preliminary implementation of Firefox Health Report
  • CHANGED
    Ability to restore removed thumbnails on New Tab Page
  • CHANGED
    CSS -moz-user-select:none selection changed to improve compatibility with -webkit-user-select:none (bug 816298)
  • CHANGED
    Graphics related performance improvements (bug 809821)
  • CHANGED
    Removed E4X support from Spidermonkey
  • DEVELOPER
    Implemented Remote Profiling
  • DEVELOPER
    Integrated add-on SDK loader and API libraries into Firefox
  • HTML5
    Added support for <main> element
  • HTML5
    Implemented scoped stylesheets
  • HTML5
    Added support for window.crypto.getRandomValues
  • FIXED
    Some function keys may not work when pressed (833719)
  • FIXED
    Browsing and Download history clearing needs unification to avoid confusion on clearing download history (847627)
  • FIXED
    21.0: Security fixes can be found here

Known Issues

  • Unresolved
    Unreadable text for some italic-styled text on Hebrew Windows system (see 837498)
    Unresolved on v21 Resolved in v22
  • Unresolved
    Fullscreen playback support for Nvidia HTML 5 Stereo Mode on 3D videos on YouTube is broken (see 869866)
  • Unresolved
    If you try to start Firefox using a locked profile, it will crash (see 573369)
  • Unresolved
    Download statusbar add-on continues downloading files from Normal Browsing, when switching to Private Browsing (see 853463)