Firefox Profiler Dark Mode and Updated Smart Window Prompts – These Weeks in Firefox: Issue 197

Friends of the Firefox team

Resolved bugs (excluding employees)

Volunteers that fixed more than one bug

• Beatriz Rizental
• Chris Vander Linden
• Khalid AlHaddad

New contributors (🌟 = first patch)

• 🌟Alex Leykin [:alexff]: Firefox’s new ‘pinned web apps / taskbar web apps’ windows (Firefox 143 on Windows 11) don’t remember their size or position after being moved/resized and reopened
• 🌟Jacob: downloaded files do not respect referrer-policy when setting kMDItemWhereFroms
•  Leonardo Paffi: Add capability for loadTestPage to take inline HTML
•  Phil [:phigl]: Request size is wrong when request is served from cache

Project Updates

Add-ons / Web Extensions

Addon Manager & about:addons

• Fixed issue hit by concurrent installations due to error handling potentially removing the entire staging directory used by the other concurrent XPI files pending installation – Bug 2006512
• Fixed issue with “Available Updated” badge counter getting out of sync – Bug 1548836

WebExtensions Framework

• Disabled dom.keyboardevent.init_key_event.enabled_in_addons preference on all channels – Bug 2015079 / Bug 2013772
  • NOTE: 1Password 4.x relied on a deprecated, non-standard API (initKeyEvent) in Firefox. The deprecated feature has been disabled for the release channel in Firefox versions >= 147. Users still using the discontinued 1password classic extension should migrate to the maintained 1password extension or migrate to another maintained password manager.
• Investigated and fixed excessive process creation on rapidly clicking extension icons (e.g., uBlock) – Bug 1987679 / Bug 2007742

WebExtension APIs

• Exposed splitViewId property in tabs extension API to support split view feature – Bug 1993037
• Improved cross-browser compatibility for the browserAction and pageAction openPopup API method, in particular allowing it to be called without user interaction (which is an ability that password managers leverages) – Bug 1799344 / Bug 1799347 / Bug 2011516
• Fixed issue with browser.storage.onChanged API event not emitted for object writes after opening Storage tab in DevTools – Bug 1994355
• Deprecating executeScript API methods support for dynamically executing code into moz-extension documents – Bug 2011234
• NOTE: This deprecation is in the process of being documented and communicated to extensions developers. The restriction is active by default on Nightly, whereas it will be logging a deprecation warning on Beta and Release channels.

DevTools

• Chris Vander Linden refactored AccessibilityRow.js and accessibility/panel.js to use proper ES private fields (#2015237, #2015238)
• Phil [:phigl] fixed the request size of cached request in Netmonitor (#1973003)
• Nicolas Chevobbe [:nchevobbe] added tooltip to show value of attribute in attr() function (#2011646)

• Julian Descottes [:jdescottes] made it possible to use Network Throttling in the Browser Toolbox (#2015030)
• Nicolas Chevobbe [:nchevobbe] fixed an issue where the content dialog (e.g. alert()) were covering the DevTools toolbox (#2013120)
• Nicolas Chevobbe [:nchevobbe] added inactive CSS indicator for position-area when the element is not absolutely positioned, and/or doesn’t have a default anchor  (#1895185)
• Julian Descottes [:jdescottes] similarly fixed an issue with the Browser Screenshot popup being displayed oddly when RDM is enabled (#2016109)

New Tab Page

• With the startup crash fixed, train-hopping has been unblocked! 149.1.20260121.51415 went out to the release and beta channels recently.
• Nathan Barrett fixed reordered Top Sites showing mismatched names/icons after restart when placed after Add Shortcut, correcting persisted tile indexing in Activity Stream so Top Sites render with the right metadata across sessions.
• Maxx Crawford added thumbnail attachment to uploaded wallpapers, using the generated thumbnail for previews in the Customize panel to speed image rendering and reduce decode cost while keeping full‑res when applied.
• Nathan Barrett enabled the image proxy backend for newtab, giving us the ability to route newtab image requests through a third-party proxy for better privacy characteristics. This is disabled by default while we investigate proxying strategies.
• Mike Conley added activation window experiment messaging variants on newtab. This is something we expect to experiment with for new installs starting later this month.
• Maxx Crawford replaced the Weather widget context menu with the shared panel‑list, unifying menu styling and improving keyboard/focus behavior on the New Tab Page.
• Irene Ni removed auto-placement logic for the Weather widget, preventing unexpected moves and reducing layout shifts so the widget consistently stays where users place it.