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Firefox 3 Release Candidate Release Notes

Firefox 3 (Release Candidate) Release Notes

Released: May 16, 2008

This Firefox 3 Release Candidate is a preview release of Mozilla's next generation Firefox browser and is being made available for testing purposes only.

Preview releases are published to collect feedback from Web developers and our testing community 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 all of their add-ons to work properly with this preview release.

Please see below for an extensive list of features and enhancements found in Firefox 3, 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 Gecko 1.9 Web rendering platform, which has been under development for the past 33 months. Building on the previous release, Gecko 1.9 has more than 14,000 updates including some major re-architecting to provide improved performance, stability, rendering 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 more under the hood to offer website and Firefox add-on developers.

More Secure
  • One-click site info: Click the site favicon in the location bar to see who owns the site and to check if your connection is protected from eavesdropping. Identity verification is prominently displayed and easier to understand. When a site uses Extended Validation (EV) SSL certificates, the site favicon button will turn green and show the name of the company you're connected to. (Try it here!)
  • Malware Protection: malware protection warns users when they arrive at sites which are known to install viruses, spyware, trojans or other malware. (Try it here!)
  • New Web Forgery Protection page: the content of pages suspected as web forgeries is no longer shown. (Try it here!)
  • New SSL error pages: clearer and stricter error pages are used when Firefox encounters an invalid SSL certificate. (Try it here!)
  • 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.
  • Effective top-level domain (eTLD) service better restricts cookies and other restricted content to a single domain.
  • 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.
  • New Download Manager: the revised download manager makes it much easier to locate downloaded files, and you can see and search on the name of the website where a file came from. Your active downloads and time remaining are always shown in the status bar as your files download.
  • 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, or optionally only the text size. Your settings will be remembered whenever you return to the site.
  • Podcasts and Videocasts can be associated with your media playback tools.
  • 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 Windows: Firefox now has improved Windows icons, and uses native user interface widgets in the browser and in web forms.
  • Integration with the Mac: the new Firefox theme makes toolbars, icons, and other user interface elements look like a native OS X application. Firefox also uses OS X widgets and supports Growl for notifications of completed downloads and available updates. A combined back and forward control make it even easier to move between web pages.
  • 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.
  • 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. Results are returned according to their frecency (a combination of frequency and recency of visits to that page) ensuring that you're seeing the most relevant matches. An adaptive learning algorithm further tunes the results to your patterns!
  • 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.
  • 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. Create and restore full backups whenever you want.
  • 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).
  • Download & Install Add-ons: the Add-ons Manager (Tools > Add-ons) can now be used to download and install a Firefox customization from the thousands of Add-ons available from our community add-ons website. When you first open the Add-ons Manager, a list of recommended Add-ons is shown.
  • 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.
  • 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
  • Speed: improvements to our JavaScript engine as well as profile guided optimizations have resulted in continued improvements in performance. Compared to Firefox 2, web applications like Google Mail and Zoho Office run twice as fast in Firefox 3, and the popular SunSpider test from Apple shows improvements over previous releases.
  • Memory usage: Several new technologies work together to reduce the amount of memory used by Firefox 3 over a web browsing session. Memory cycles are broken and collected by an automated cycle collector, a new memory allocator reduces fragmentation, hundreds of leaks have been fixed, and caching strategies have been tuned.
  • 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.

Downloading and Installing

System Requirements

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

Downloading Firefox 3

Mozilla provides Firefox 3 for Windows, Linux, and Mac OS X in a variety of languages. You can get the latest version of Firefox 3 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

Please note that installing Firefox 3 will overwrite your existing installation of Firefox on Mac OS X and Linux. On Windows, Firefox 3 installs in a new folder. For all systems, 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

You can remove Firefox 3 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 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 will continue to use the data from this profile folder.

Extensions and Themes

Extensions installed under previous versions of Firefox may be incompatible and/or require updates to work with Firefox 3. Please report any issues to the maintainer of the extension.

When you install Firefox 3 all of your Extensions and Themes will be disabled until Firefox 3 determines that either a) they are compatible with the Firefox 3 release or b) there are newer versions available that are compatible.

Known Issues

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

All Systems
  • Installing Firefox 2 in the same directory in which Firefox 3 has been installed may result in Firefox 2 being unstable (bug 423226)
  • If Flash content is active when Firefox crashes, the Crash Reporter may not activate (bug 422308)
  • Deleting an entry from the history sidebar, then invoking the Clear Private Data tool can result Firefox crashing (bug 426275)
  • Some add-ons that depend on deprecated code may not install properly (see bug 406807)
  • Privacy > History > Remember visited pages to "0" has no effect (bug 366075)
  • The DOM Inspector has been removed and is now available as an add-on.
  • Support for Cross-Site XmlHttpRequest has been removed until the specification becomes more stable and the security model is improved (bug 424923)
  • After dismissing the "Do you want Firefox to remember this password" prompt, it is sometimes not possible to focus form fields unless you reload the page (bug 433942)
  • The new Location Bar, Add Bookmark dialog, and Download Manager information popup behave inconsistently with Window-Eyes. JAWS 8.0 or better is recommended for this release candidate. (bug 393398)
Microsoft Windows
  • A Windows Media Player (WMP) plugin is not provided with Windows Vista and some other versions of Windows. To view Windows Media content, you must install this plugin by following these instructions. After installing you may need to check for Windows Updates before the plugin will show content properly.
Mac OS X
  • Items in the "File" menu show as inactive after using the "Print" item from that menu - switching to a new tab restores them (bug 425844)
Linux and Unix
  • If your screen resolution is 800x600 or smaller, you may not be able to see the "Accept" button on the End User License Agreement. Keyboard commands can be used to accept the agreement (bug 433298)
  • Ubuntu users who download and install Firefox may find that they cannot install add-ons without first deleting their extensions.rdf file (bug 433371)
  • Users running Ubuntu 7.10 may need to update their certificate databases in order to submit crash reports (bug 407748 for instructions)
  • The mouse button assignments for Back and Forward have changed, users may need to reconfigure their pointing devices (bug 420294)
  • Incompatibilities between NVIDIA drivers and some versions of the X server cause scaled images to render incorrectly (bug 411831)
  • The Orca screen reading software does not read some text, such as the save password notification, site identity information, or the default prompt text in search fields - these are known problems with Orca (see Gnome bug 533109 and 533125)


  • 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.

    If you're interested in helping us test pre-release builds, you might want to join our beta test mailing list.

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

    Use the newsgroup. The Firefox team reads it regularly, and your email may have gotten 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?

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

  5. Where's the Firefox 3 source code?

    A tarball of the Firefox 3 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 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.

The following resources contain useful information about Firefox 3: