Mozilla’s latest Firefox update introduces wider access to its AI-driven Smart Window in France, enhancing search speed, organisation, and privacy features while addressing platform-specific bugs and developer constraints.
Mozilla has released Firefox 155.0, widening access to its AI-driven Smart Window to users in the United States, Canada and France. The feature had already been available in the US and Canada since Firefox 150, but this is the first release to include France. Mozilla is still rolling the feature out gradually, so eligible users may not see it immediately. The company says the staged approach helps it catch problems before completing distribution. Mozilla describes Smart Window as an optional browser window built around an AI assistant that can work with open tabs and browsing history.
For users who already have the feature, Mozilla says the assistant now surfaces Exa web search citations about five times faster than before. It also adds personalised resume prompts when a person returns to an earlier topic, while the tab-organisation tool now suggests more coherent groups and clearer labels. These changes are part of a broader effort to make the assistant more useful without making it mandatory.
Firefox 155.0 also brings a series of interface and privacy-related changes. A blocked-tracker count now appears in the address bar for the first time, although turning it off only hides the number and does not disable tracking protection. Container tabs can now be rearranged from Firefox’s settings page, with the order carrying through to menus, tab labels and prompts. On Windows, Nintendo Switch Pro controllers and compatible third-party pads now work properly in browser games, while Firefox’s built-in translation tool adds Marathi and Urdu.
The release also fixes a long list of platform-specific bugs. Mozilla says Linux users should no longer see sleep prevention after extended browsing, and Microsoft 365 Word Online should no longer drop text under certain keyboard layouts. On macOS, full-screen video should display correctly on MacBooks with a notch, and a WebCodecs encoder hang has been fixed. Windows users should no longer see missing glyphs for some scripts, while several cross-platform faults have also been addressed, including live audio streams stopping in background tabs and text in buttons becoming unselectable.
For developers and network administrators, Firefox 155.0 introduces stricter limits on CSS nesting, which Mozilla says now tops out at 75 levels to prevent crashes from deeply nested stylesheets. The browser’s captive portal detection endpoint has also moved, meaning any firewall or proxy rules built around the old domain will need updating. Mozilla has additionally changed how mailto: links behave so they cannot launch a default mail client without direct user action. The release also includes security fixes covered by advisory MFSA 2026-82.
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