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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.

53.0a2

Firefox Developer Edition

January 27, 2017

Version 53.0a2, first offered to Firefox Developer Edition channel users on January 27, 2017

For more information about Developer Edition please see this MDN article.

New

  • Improved graphics stability for Windows users with the addition of compositor process separation (Quantum Compositor)

  • Two new 'compact' themes available in Firefox, dark and light, based on the Firefox Developer Edition theme

  • Lightweight themes are now applied in private browsing windows

  • Reader Mode now displays estimated reading time for the page

  • New installs on Win7+ 64 bit OS now default to 64 bit Firefox

Changed

  • Windows XP and Vista are no longer supported. XP and Vista users running Firefox 52 will continue to receive security updates on Firefox ESR 52.

  • 32-bit Mac OS X is no longer supported. 32-bit Mac OS X users can switch to Firefox ESR 52 to continue receiving security updates.

  • The last few characters of shortened tab titles fade out instead of being replaced by ellipses to keep more of the title visible

  • Media playback on new tabs is blocked until the tab is visible

  • Process separation (e10s) now supported on Windows 10 touch screen devices and systems with accessibility tools installed

  • Select menus offer an inline search when the menus are over 40 items

  • Ended Firefox Linux support for processors older than Pentium 4 and AMD Opteron

  • New visual design for audio and video controls

Developer

Developer Information