What is new?
- Firefox 4 Beta 2 is available in 24 languages.
- Tabs are now on top by default on Windows and OSX – Linux will be changing when the theme has been modified to support the change.
- You can turn any tab into an “App Tab” by right-clicking on it and selecting “Make into App Tab” from the context menu.
- Web developers can animate content using CSS Transitions.
- Responsiveness and scrolling improvements from the new retained layers layout system.
- Changes to how XPCOM components are registered in order to help startup time and process separation.
- See the complete changelist from the previous beta.
As well as these features from previous Firefox 4 Betas:
- You can search for and switch to already open tabs in the Smart Location Bar
- New Addons Manager and extension management API (UI will be changed before final release)
- Significant API improvements are available for JS-ctypes, a foreign function interface for extensions.
- The stop and reload buttons have been merged into a single button on Windows, Mac and Linux.
- The Bookmarks Toolbar has been replaced with a Bookmarks Button by default (you can switch it back if you’d like).
- Crash protection for Windows, Linux, and Mac when there is a crash in the Adobe Flash, Apple Quicktime or Microsoft Silverlight plugins.
- CSS Transitions are partially supported.
- Full WebGL support is included but disabled by default at this time.
- Core Animation rendering model for plugins on Mac OS X. Plugins which also support this rendering model can now draw faster and more efficiently.
- Native support for the HD HTML5 WebM video format.
- An experimental Direct2D rendering backend is available on Windows, turned off by default.
- Web developers can use Websockets for a low complexity, low latency, bidirectional communications API.
- Web developers can update the URL field without reloading the page using HTML History APIs.
- More responsive page rendering using lazy frame construction.
- Link history lookup is done asynchronously to provide better responsiveness during pageload.
- CSS :visited selectors have been changed to block websites from being able to check a user’s browsing history.
- New HTML5 parser.
- Support for more HTML5 form controls.
Before installing, make sure your computer meets the system requirements:
Please note that Linux distributors may provide packages for your distribution which have different requirements. Firefox will not run at all without the following libraries or packages:
For optimal functionality, following libraries or packages recommended:
Mozilla will provide Firefox 4 Beta for Windows, Linux, and Mac OS X in a variety of languages, though this first version is only available in English. Eventually you will be able to get the latest version of the Firefox 4 Beta in many languages. For builds for other systems and languages not provided by Mozilla, see the Contributed Builds section at the end of this document.
Installing Firefox 4 Beta will not 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.
You can remove Firefox 4 Beta with the Add/Removes Programs utility on Windows, by moving the Firefox application to the Trash on OS X, or by deleting the containing folder on Linux.
By default, removing Firefox 4 Beta won’t remove your bookmarks, web browsing history, extensions or other add-ons. This data is stored in your profile folder, which can be found by going to the Help menu and selecting Troubleshooting Information…. The button next to the Profile Directory line in Application Basics will open your profile directory in your system’s file explorer.
Please note that if you keep your profile, any version of Firefox that you install after removing Firefox 4 Beta will continue to use the bookmarks, web browsing history, add-ons, and other data from this profile folder.
Add-ons and Themes
Add-ons installed with previous versions of Firefox may not yet have been updated by their authors to work with this Firefox 4 Beta. If you wish to help test Add-ons, please install the Add-on Compatibility Reporter – your favorite Add-on author will appreciate it!
This list covers some of the known problems with Firefox 4 Beta which will be resolved in future versions:
- All Systems
- For some users, scrolling in the main GMail window will be slower than usual (see bug 579260)
- Some plugin content, like the media controls on older YouTube videos, will be initially drawn incorrectly. Scrolling or hovering over the affected areas restores them (see bug 579262)
- The popular video sites Hulu.com and Netflix.com are not displaying content to beta users due to bad “user-agent” detection in their code (see bug 580843 and bug 522957)
- The Bookmark Toolbar is turned off by default even on existing profiles (see bug 574514)
- If you try to start Firefox using a locked profile, it will crash (see bug 573369)
- Microsoft Windows
- This beta will not start on Windows 2000 (see bug 577486)
- A rendering problem with Google Finance can lead to instability (see bug 579558)
- Some graphics drivers may not work properly with full screen Ogg Theora HTML video acceleration (see bug 564391)
- When using a Persona, the maximize, minimize and close window buttons will not appear, though they will still work (see bug 574833)
- When using the Windows “Classic” theme the toolbars and tab strip may appear gray for several seconds as Firefox starts up (see bug 574638)