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Firefox 3 Beta Release Notes

Released: December 18, 2007

Firefox 3 Beta 2 is a developer preview release of Mozilla's next generation Firefox browser and is being made available for testing purposes only.

These beta releases are targeted to Web developers and our testing community to gain feedback before advancing to the next stage in the release process. The final version of Firefox 3 will be released when we qualify the product as fully ready for our users. Users of the latest released version of Firefox should not expect their add-ons to work properly with this beta.

Much of the work leading up to this beta has been around developing the infrastructure to support a bunch of exciting new features. With this second beta, you'll get a taste of what's coming in Firefox 3, but there's still more to come, and much of what you'll see is still a bit rough around the edges.

Please see below for an extensive list of features and enhancements found in Firefox 3 Beta 2, as well as known issues and frequently asked questions.

As always, we appreciate your feedback either through this feedback form or by filing a bug in Bugzilla.

What's New in Firefox 3

Firefox 3 is based on the new Gecko 1.9 Web rendering platform, which has been under development for the past 28 months and includes nearly 2 million lines of code changes, fixing more than 11,000 issues. Gecko 1.9 includes some major re-architecting for performance, stability, correctness, and code simplification and sustainability. Firefox 3 has been built on top of this new platform resulting in a more secure, easier to use, more personal product with a lot under the hood to offer website and Firefox add-on developers.

[Improved in Beta 2!] Firefox 3 Beta 2 includes approximately 900 improvements over the previous beta, including fixes for stability, performance, memory usage, platform enhancements and user interface improvements. Many of these improvements were based on community feedback from the previous beta.

More Secure
  • One-click site info: Click the site favicon in the location bar to see who owns the site. Identity verification is prominently displayed and easier to understand. In later versions, Extended Validation SSL certificate information will be displayed.
  • Malware Protection: malware protection warns users when they arrive at sites which are known to install viruses, spyware, trojans or other malware. You can test it here (note: our blacklist of malware sites is not yet activated).
  • New Web Forgery Protection page: the content of pages suspected as web forgeries is no longer shown. You can test it here.
  • New SSL error pages: clearer and stricter error pages are used when Firefox encounters an invalid SSL certificate.
  • Add-ons and Plugin version check: Firefox now automatically checks add-on and plugin versions and will disable older, insecure versions.
  • Secure add-on updates: to improve add-on update security, add-ons that provide updates in an insecure manner will be disabled.
  • Anti-virus integration: Firefox will inform anti-virus software when downloading executables.
  • Vista Parental Controls: Firefox now respects the Vista system-wide parental control setting for disabling file downloads.
  • [Improved in Beta 2!] Effective top-level domain (eTLD) service better restricts cookies and other restricted content to a single domain.
  • [Improved in Beta 2!] Better protection against cross-site JSON data leaks.
Easier to Use
  • Easier password management: an information bar replaces the old password dialog so you can now save passwords after a successful login.
  • Simplified add-on installation: the add-ons whitelist has been removed making it possible to install extensions from third-party sites in fewer clicks.
  • [Improved in Beta 2!] New Download Manager: the revised download manager makes it much easier to locate downloaded files, and displays where a file came from.
  • Resumable downloading: users can now resume downloads after restarting the browser or resetting your network connection.
  • Full page zoom: from the View menu and via keyboard shortcuts, the new zooming feature lets you zoom in and out of entire pages, scaling the layout, text and images.
  • Tab scrolling and quickmenu: tabs are easier to locate with the new tab scrolling and tab quickmenu.
  • Save what you were doing: Firefox will prompt users to save tabs on exit.
  • Optimized Open in Tabs behavior: opening a folder of bookmarks in tabs now appends the new tabs rather than overwriting.
  • Location and Search bar size can now be customized with a simple resizer item.
  • Text selection improvements: multiple text selections can be made with Ctrl/Cmd; double-click drag selects in "word-by-word" mode; triple-clicking selects a paragraph.
  • Find toolbar: the Find toolbar now opens with the current selection.
  • Plugin management: users can disable individual plugins in the Add-on Manager.
  • Integration with Vista: Firefox's menus now display using Vista's native theme.
  • Integration with the Mac: Firefox now uses the OS X spellchecker and supports Growl for notifications of completed downloads and available updates.
  • [Improved in Beta 2!] Integration with Linux: Firefox's default icons, buttons, and menu styles now use the native GTK theme.
More Personal
  • Star button: quickly add bookmarks from the location bar with a single click; a second click lets you file and tag them.
  • Tags: associate keywords with your bookmarks to sort them by topic.
  • [Improved in Beta 2!] Location bar & auto-complete: type in all or part of the title, tag or address of a page to see a list of matches from your history and bookmarks; a new display makes it easier to scan through the matching results and find that page you're looking for.
  • [Improved in Beta 2!] Smart Bookmarks Folder: quickly access your recently bookmarked and tagged pages, as well as your more frequently visited pages with the new smart bookmarks folder on your bookmark toolbar.
  • [Improved in Beta 2!] Places Organizer: view, organize and search through all of your bookmarks, tags, and browsing history with multiple views and smart folders to store your frequent searches.
  • [Improved in Beta 2!] Web-based protocol handlers: web applications, such as your favorite webmail provider, can now be used instead of desktop applications for handling mailto: links from other sites. Similar support is available for other protocols (Web applications will have to first enable this by registering as handlers with Firefox).
  • Easy to use Download Actions: a new Applications preferences pane provides a better UI for configuring handlers for various file types and protocol schemes.
Improved Platform for Developers
  • New graphics and font handling: new graphics and text rendering architectures in Gecko 1.9 provides rendering improvements in CSS, SVG as well as improved display of fonts with ligatures and complex scripts.
  • Native Web page forms: HTML forms on Web pages now have a native look and feel on Mac OS X and Linux (Gnome) desktops.
  • Color management: (set gfx.color_management.enabled on in about:config and restart the browser to enable.) Firefox can now adjust images with embedded color profiles.
  • Offline support: enables web applications to provide offline functionality (website authors must add support for offline browsing to their site for this feature to be available to users).
  • A more complete overview of Firefox 3 for developers is available for website and add-on developers.
Improved Performance
  • Reliability: A user's bookmarks, history, cookies, and preferences are now stored in a transactionally secure database format which will prevent data loss even if their system crashes.
  • [Improved in Beta 2!] Speed: Major architectural changes (such as the move to Cairo and a rewrite to how reflowing a page layout works) put foundations in place for major performance tuning which have resulted in speed increases in Beta 2, and will show further gains in future Beta releases.
  • [Improved in Beta 2!] Memory usage: Over 300 individual memory leaks have been plugged, and a new XPCOM cycle collector completely eliminates many more. Developers are continuing to work on optimizing memory use (by releasing cached objects more quickly) and reducing fragmentation. Beta 2 includes over 30 more memory leak fixes, and 11 improvements to our memory footprint.

Downloading and Installing

System Requirements

Before installing, make sure your computer meets the system requirements.

Downloading Firefox 3 Beta 2

Mozilla provides Firefox 3 Beta 2 for Windows, Linux, and Mac OS X in a variety of languages. You can get the latest version of Firefox 3 Beta 2 here. For builds for other systems and languages not provided by, see the Contributed Builds section at the end of this document.

Installing Firefox 3 Beta 2

Please note that installing Firefox 3 Beta 2 will overwrite your existing installation of Firefox. You won't lose any of your bookmarks or browsing history, but some of your extensions and other add-ons might not work until updates for them are made available.

Removing Firefox 3 Beta 2

You can remove Firefox 3 Beta 2 through the Control Panel in the Start Menu on Windows, by removing the Firefox application on OS X, or by removing the firefox folder on Linux.

Removing Firefox 3 Beta 2 won't remove your bookmarks, web browsing history, extensions or other add-ons. This data is stored in your profile folder, which is located in one of the following locations depending on your operating system:

Windows Vista Users\<UserName>\AppData\Roaming\Mozilla\Firefox
Windows 2000, XP, Server 2003 Documents and Settings\<UserName>\Application Data\Mozilla\Firefox
Mac OS X ~/Library/Application Support/Firefox
Linux and Unix systems ~/.mozilla/firefox

Any version of Firefox that you install after removing Firefox 3 Beta 2 will continue to use the data from this profile folder.

Extensions and Themes

Extensions installed under Firefox 2 may be incompatible and/or require updates to work with Firefox 3 Beta 2. Please report any issues to the maintainer of the extension. When you install Firefox 3 Beta 2 all of your Extensions and Themes will be disabled until Firefox 3 Beta 2 determines that either a) they are compatible with the Firefox 3 Beta 2 release or b) there are newer versions available that are compatible.

Known Issues

This list covers some of the known problems with Firefox 3 Beta 2. Please read this before reporting any new bugs.

All Systems
  • Privacy > History > Remember visited pages to "0" has no effect (bug 366075)
  • MathML does not render properly in Firefox 3 Beta 2 (bug 324857)
  • Yahoo! Mail will not work; users must use Yahoo! Classic Mail (bug 398381)
  • Windows Live Mail will not work; users must use Hotmail Classic Mail (bug 396259)
  • Cannot drag and drop folders in the Places Organizer, for now users must use cut and paste (bug 405198)
  • The new Location Bar, Add Bookmark dialog and Download Manager Information popup behave inconsistently with Window-Eyes and JAWS 9.0. Using JAWS 8.0 is recommended for this beta. (bug 407359 and bug 393398)
  • The malware and phishing protection feature is not getting new data quickly enough, and may not work as expected (bug 402469)
  • The phishing protection blacklist is not currently activated
  • Using the Internet Download Manager add-on will cause Firefox to crash; it should be disabled or uninstalled (bug 382356)
  • Using the ChatZilla add-on will cause Firefox to crash; it should be disabled or uninstalled (bug 407034)
  • Cannot create new profiles with the Profile Manager in Turkish localized builds, use command line arguments instead (bug 408199)
  • Web feeds served as text/html won't load properly (bug 381357)
Microsoft Windows
  • Crash reports cannot be sent from machines running Windows Vista (bug 390568)
  • Non-administrator Vista users are unable to launch Firefox if Vista Parental controls are enabled (bug 396509)
  • A Windows Media Player (WMP) plugin is not provided with Windows Vista. As a workaround, in order to view Windows Media content, you can follow these instructions. Note that after installing you may have to get a security update and apply it before you can see the content in the browser.
Mac OS X
  • Placing the cursor in the location bar or text fields sometimes doesn't work (bug 354768)
Linux and Unix
  • Restarting Firefox from the crash reporter doesn't work on Fedora 8 (bug 407229)
  • Some GTK themes fail to properly render the disabled state of checkboxes and radiobuttons (see bug 388131)
  • Some icons are missing on 64-bit Ubuntu installations (bug 402742)


  • Poorly designed or incompatible extensions can cause problems with your browser, including make it crash, slow down page display, etc. If you encounter strange problems relating to parts of the browser no longer working, the browser not starting, windows with strange or distorted appearance, degraded performance, etc, you may be suffering from Extension or Theme trouble. Restart the browser in Safe Mode. On Windows, start using the "Safe Mode" shortcut created in your Start menu or by running firefox.exe -safe-mode. On Linux, start with ./firefox -safe-mode and on Mac OS X, run:

    cd /Applications/
    ./firefox-bin -safe-mode

    When started in Safe Mode all extensions are disabled and the Default theme is used. Disable the Extension/Theme that is causing trouble and then start normally.
  • If you uninstall an extension that is installed with your user profile (i.e. you installed it from a Web page) and then wish to install it for all user profiles using the -install-global-extension command line flag, you must restart the browser once to cleanse the profile extensions datasource of traces of that extension before installing with the switch. If you do not do this you may end up with a jammed entry in the Extensions list and will be unable to install the extension globally.
  • If you encounter strange problems relating to bookmarks, downloads, window placement, toolbars, history, or other settings, it is recommended that you try creating a new profile and attempting to reproduce the problem before filing bugs. Create a new profile by running Firefox with the -P command line argument, choose the "Manage Profiles" button and then choose "Create Profile...". Migrate your settings files (Bookmarks, Saved Passwords, etc) over one by one, checking each time to see if the problems resurface. If you do find a particular profile data file is causing a problem, file a bug and attach the file.

Frequently Asked Questions

  1. What can I do to help?

    We need help from developers and the testing community to provide as much feedback as possible to make Firefox even better. Please read these notes and the bug filing instructions before reporting any bugs to Bugzilla. You can also give us your feedback through this feedback form.

  2. Why haven't you responded to the mail I sent you?

    Use the forums. The Firefox team reads them regularly. We all get a lot of email and your email may get lost.

  3. Where can I get extensions and themes (add-ons)?

    Extensions and Themes can be downloaded from Firefox Add-ons.

  4. Who makes Firefox 3 Beta 2?

    Lots of people. See Help->About Mozilla Firefox, Credits for a list of some of the people who have contributed to Firefox 3 Beta 2.

  5. Where's the Firefox 3 Beta 2 source code?

    A tarball of the Firefox 3 Beta 2 source code is available for download. The latest development code can be obtained by cvs. Firefox-specific source is in "mozilla/browser", "mozilla/toolkit", and "mozilla/chrome". Please follow the build instructions.

  6. Where is the mail client?

    Firefox 3 Beta 2 works with whatever mail client is the default on your system. However, we recommend Mozilla Thunderbird, our next-generation email client and the perfect complement to Firefox.

Contributed Builds

Many localized builds are now produced and distributed by on behalf of their authors. These are available on the Firefox 3 Beta 2 download page.

Builds that have not yet been certified as official Firefox 3 Beta 2 localizations are available by browsing the FTP site.

These are unofficial builds and may be configured differently than the official builds. They may also be optimized and/or tested for specific platforms.

The following resources contain useful information about Firefox 3 Beta 2: