Download Firefox Developer Edition (eo) 147.0

New
- WebGPU support is now enabled for all macOS versions on devices with Apple Silicon processors.
- Zero copy video of hardware decoded video with AMD GPUs if supported, improving video playback performance on those systems.
- Firefox now supports the Freedesktop.org XDG Base Directory Specification.
- Firefox now supports the Safe Browsing V5 protocol and is migrating from Safe Browsing V4 to the local list mode of Safe Browsing V5 protocol.
- We've added a new feature to automatically open a Picture-in-Picture player window for a playing video in a tab if that tab is ever backgrounded. This feature was mainly contributed by a volunteer Daniele Ferla, and has recently graduated from Firefox Labs! You can turn this feature on by visiting about:settings and checking "Keep playing videos in Picture-in-Picture when switching tabs".
- Firefox 147 includes support for Compression Dictionaries, IETF RFC 9842. This can significantly reduce the number of bytes transferred to load a page in several ways. That can lead to faster pageloads, especially for users with restricted bandwidth. Several major sites are currently using this, and likely many more will in the next year.
Fixed
- A draggable button is now draggable if the drag is started from the button itself.
- Fixed an issue that prevented Windows users from selecting a tab when the cursor was at the top of the screen and Firefox was maximized on some kinds of monitors.
- For Linux GNOME Mutter users, window and rendering surface sizes were updated to match the actual pixel grid so Firefox delivers sharp rendering on fractionally scaled displays regardless of actual window size.
- Fixed a bug that made HTTP/3 requests containing non-UTF-8 header values time out or fallback to HTTP/2 after awhile.
Changed
- Firefox now uses the same quality values (q-values) in Accept-Language headers as other major browsers. The second language preference is now sent with q=0.9 instead of q=0.5, with subsequent languages decreasing by 0.1 each (minimum 0.1). This change fixes compatibility issues with some servers that incorrectly rejected requests with lower quality values.
Developer

Web Platform
- Added support for the Navigation API. This API provides the ability to initiate, intercept, and manage browser navigation actions. It is a successor to previous web platform features such as the History API and window.location, which solves their shortcomings.
- The CSS counter-* and quotes properties are now supported in the ::marker pseudo-element.
- Both CompressionStream and DecompressionStream now support the Brotli format.
- Firefox now exposes the view transition currently active on the document via the Document.activeViewTransition property.
- Firefox now supports the :active-view-transition-type selector and associated View Transitions API changes.
- CSS Module Scripts allow stylesheets to be imported using the JavaScript module system and import attributes, for more information, please see https://developer.mozilla.org/docs/Web/JavaScript/Guide/Modules#loading_non-javascript_resources.
- Support for CSS anchor positioning was added, which allows to tether elements together. The anchor-positioned elements can then have their size and position set relative to the size and location of the anchor elements to which they are bound.
- Firefox now supports Storage-Access-Headers allowing servers to opt-in into unpartitioned cookies via HTTP headers if storage-access was granted prior with the Storage-Access-API.
- Module service workers are now supported, aligning Firefox with other major browsers and improving compatibility for modern web apps.
- Implemented CSS root-font-relative units rcap, rch, rex and ric.