Version 42.1

• Updated to support Firefox 42
• Replaced #2e3436 to ButtonText
• Return default icons on about:addons page
• Fixed sidebar border color
• Add support for Mozilla Archive Format extension
• Replaced "Deprecated" tooltip to description
• Added "Disable tab animation" tweak
• Updated Polish translation (@piotrdrag)

Version 40.1

• Support Firefox 40+
• Full support for "Tree Style Tab" extension (be sure to choose "default" for the theme in the extension's settings)
• Changed tabs now show a blue dot instead of a glow
• Updated translations for Polish
• Improved tab sizing
• Misc. bugfixes and theme improvements

Version 38.1

• Firefox 38.0.1 - 41.x (nightly) support
• Improved dark variant (tabs, panel menu button color, etc.)
• Improved icons (uBlock, Evernote, chat)

Version 35.1

Changelog:

• Firefox 35 support
• Firefox Hello support (new in Firefox 35)
• Pushbullet extension support
• Updated toolbarbutton & subview styling
• Updated AdBlock plus icon (dark mode support)
• French translation

Version 34.1

Enhancements:

• Adopted GNOME 3.14 three-line menu button (often called "hamburger" or "hotdog" icon)
• Updated tabs style
  • Officially updated to GNOME 3.12+ tabs style (removed "Show tabs on top", "GNOME 3.12 style tabs", and "Hide white border after tabs toolbar")
• Added support for GNOME Tweak's option to disable e10s tab underline
• German translation

Fixes:

• HTitle 3 support
• Tabs toolbar shadows

Supports Firefox 34+

Complete changelog: 33.1...34.1

Version 33.1

Change log:

• New icons for Forget and Apps buttons.
• Add Omnibar extension support.
• Bug fixes.

Firefox 33.0 - 36.0a1 supported.

Detailed changelog since 32.1: 32.1...33.1

Version 32.1

Change log:

• New image for throbber (GNOME 3.12).
• Add "Three line icon for the menu button" tweak.
• Bug fixes.

Firefox 32.0 - 35.0a1 supported.

Detailed changelog since 31.1: 31.1...32.1

Version 31.1

Change log:

• Added indications for private windows (#263).
• Changed notifications colors (#262).
• Removed "Always show forward button" tweak (#252).
• Removed Firefox 30 support.
• Bug fixes.

Firefox 31.0 - 34.0a1 supported.

Detailed changelog since 30.1: 30.1...31.1

Version 30.1

• GNOME 3.12 style tabs (optional).
• New style for 'about:addons'
• Updated window controls and toolbarbuttons styles.
• New style for notification bar.
• New style for Addons page.
• Added symbolic icons for RequestPolicy extension (thanks to @black-roland).
• Added Ukrainian translation (thanks to @chpii).
• Updated Polish translation (thanks to @piotrdrag).
• Removed Firefox 29 support.
• Fixed RTL locales support.
• Fixed Flagfox, All-in-One Sidebar, HTitle extensions support.
• Other bug fixes.

Firefox 30 - 32.0a2 supported.

Detailed changelog since 29.1: 29.1...30.1

Version 29.1

• Added support for Australis, the new Firefox interface in Firefox 29
• New style for about: pages
• Enabled "tabs on bottom" mode by default (the GNOME Tweak Extension can change the style)
• Changed style of panels (added shadow, animations)
• Improved styles for inactive windows

Firefox 28 - 31.0a1 supported.

Detailed changelog since 28.1: 28.1...29.1