Firefox 121.0 officially released

Firefox 121.0 has been released. The specific updates are as follows:

New

• Firefox now prompts Windows users to install the Microsoft  AV1 Video Extension to about:supportenable hardware decoding support for the AV1 video codec if it is not already installed.

• Firefox now supports voice control commands on macOS systems .

• On Linux, Firefox now defaults to using the Wayland compositor (if available) instead of XWayland. This brings support for touchpad and touchscreen gestures, swipe navigation, per-monitor DPI settings, better graphics performance, and more.

  Note that due to Wayland protocol limitations, picture-in-picture windows require additional user interaction (usually right-clicking on the window) or shell/desktop environment adjustments. For related discussion and tracking, see  bug 1621261  , for KDE configuration see this post, and for GNOME extensions see this post .

• Firefox can now force links to always be underlined. This option can be enabled in the Browsing section of the Firefox settings menu.

• The PDF viewer now includes a floating button that simplifies deleting drawings, text, and images added to PDFs.

Fixed

• Various security fixes. 

Developer

• Firefox Debugger now includes a new feature: debuggerthe option to disable keywords on the current page. This feature is accessible through a new checkbox in the Breakpoints side panel, labeled " Pause on debugger statement", located next to the existing Pause on exceptionscheckbox. This option is enabled by default, which means that debugger statements will be active unless manually disabled.

  

• As part of an effort to improve the usability of Firefox developer tools, focus indicators have been unified across the toolbox. The focus indicator is now larger and higher contrast, with a white frame shadow for enhanced visibility on a blue background. Adjustments have also been made to ensure clear visibility of shared components and frequently used panels, preventing overlap with element borders or backgrounds.

 Web Platform

• :has()Selectors are now supported . This allows authors to match elements that have or "anchors" at least one element that matches their relative selector.

• The text  -indent  CSS property now supports hangingand each-linekeywords, providing more convenient paragraph layout options for bibliography, poetry, and other styles.

• The text-wrap  CSS property now supports balancekeywords, which can improve the appearance of short multi-line blocks of text (such as long titles or captions) by coordinating line lengths.

• Lazy loading<iframe loading=lazy> iframe ( ) is now supported  . Lazy loading iframes only load when visible, so non-critical iframes can be loaded later if needed to speed up the initial page load, reduce initial network usage, etc.

• Added support for tail call elimination in WebAssembly languages ​​to improve support for functional languages.

Please see the update notes for details .