Mozilla released the first beta for Firefox 4 on Tuesday, introducing a new interface design to a wider Windows audience, support for multiple technologies that aim to be essential to Web browsing in the future, and a plan for updates far more aggressive than those of the past.
The interface changes in this first beta version are the most apparent, and they might take some users time to get used to, unless you've been playing around with the Firefox nightly builds. Tabs are now on top, by default, at least in the Windows version. In its changelog, Mozilla promises that tabs-on-top will come to the Linux and Mac versions of Firefox, when the default themes on those two operating systems receive updates. This can be toggled under the Customize option under the menu button, labeled "Firefox," in the upper-left corner of the interface.
The menu button is also new to Firefox, but not to browsing in general, as Mozilla follows the lead here of other browsers. Google Chrome has always had tabs on top, and Opera earlier this year compacted its menu bar behind a single drop-down menu in the upper-left corner. Bookmarks have also received the button treatment, though you can resurrect the bookmarks bar easily enough. In this beta version of Firefox, only Windows Vista and Windows 7 users will see it.
There are other tangible changes to the browser. You can now search for open tabs from the smart location bar, and the Stop and Reload interface buttons have been merged into one. The add-on interface has been overhauled, but don't get too used to it; Mozilla says it's a work in progress, so you can expect its look to continue to evolve. Mozilla hopes to have the new, lightweight Jetpack framework in place for when Firefox 4 is out of beta testing later this year.
The out-of-process plug-in protection that debuted for Windows and Linux users in Firefox 3.6.4, but has been restricted to the beta builds for Mac, comes fully activated for all three platforms in this beta. This keeps crashes in Adobe System's Flash, Microsoft's Silverlight, and Apple's QuickTime from pulling down the entire browser.
Firefox 4 beta also sees significant improvements to Firefox under the hood. There's a new HTML5 parser, and support for more HTML5 form controls than in previously released Firefox betas or the nightly builds. The HTML5 WebM video format for HD is natively supported, and APIs have been improved for Websockets, HTML History, and JS-ctypes, a foreign function interface for extensions. CSS transitions are partially supported too.
Some features in Firefox 4 but have been turned off by default, for now, including full WebGL support and an experimental Direct2D rendering back end for Windows. Mac users will see a core animation rendering model for plug-ins on their operating system, which means that plug-ins that support it should be able to draw faster and more efficiently.
In security, Firefox 4 so far introduces a minor but useful change. CSS ":visited" selectors now prevent Web sites from checking a user's browsing history. There are plans for an account manager and a content security policy to help detect and prevent attacks.
Mozilla said in its blog post announcing the new beta version on Tuesday that users can expect updates about every two weeks. There's also a prominent "feedback" button to the right of the location bar, which Mozilla has already begun using to get feedback about the browser. The full changelog for Firefox 4 beta 1 details even more changes made to the browser, and it hints at what's coming, as development of the browser proceeds.