Firefox 4 release candidate now available

Mozilla on Wednesday released the Firefox 4 release candidate, the final update before the company formally unveils its next-generation browser.

Those who have been testing Firefox 4 will be automatically upgraded to the RC. Mozilla said it has fixed more than 8,000 bugs since the first beta release of Firefox 4, but encouraged RC users to test this latest release as well and provide feedback.

Mozilla executives expect the final Firefox 4 to be released later this month.

Firefox 4 is a major upgrade for Mozilla. It will feature a revamped plug-in architecture called JetPack, a redesigned minimalist interface, faster JavaScript performance, and greater support for HTML5, including Google's WebM HTML5 video format.

Mozilla has streamlined the user interface, collapsing the full menu bar into a small "Firefox" drop-down option on the top left. The tabs are front and center, with the URL and search bars underneath.

For those who have a lot of tabs open at one time, Firefox 4 features the ability to drag and drop tabs into separate groups, known as Panorama, which can be accessed with the click of a button. To that end, Firefox 4 also allows users to pin frequently used sites to the top left of the browser. Sites like Gmail, Twitter, or Flickr can be turned into "App Tabs," which will show up as small icons on the top left and glow slightly when new mail, tweets, or other notifications arrive. No matter how many other tabs you open, these "App Tabs" will remain on the left for easy access, and can be removed at any time.

If you access Firefox on various devices, Firefox 4 has the ability to sync settings, passwords, bookmarks, history, open tabs, and other customizations. Executives insisted that the process is secure; the data is encrypted via a 26-character key.

Firefox is known for its add-ons, and Mozilla said that more than 70 percent of its add-ons are now compatible with Firefox 4. For easier access, Firefox 4 includes an Add-On Manager that helps people discover new add-ons and manage existing ones.

The updated browser also includes a "do not track" option. The "Advanced" screen in Firefox Options will now include a box that, when checked, tells Web sites that you want to opt-out of tracking used for behavioral advertising. Mozilla added the feature to a pre-build version of Firefox in January, and added it to the beta in February.

In an interview this week, Mozilla executives said the feature is a work in progress. Since adding it to the beta, various ad networks have contacted Mozilla asking how they can be a part of the process. Most people are not that concerned about the targeted ad process, so Mozilla is exploring the option of having different levels of "do not track." It's early days at this point, the company said, but a main component is actually defining what "do not track" entails. It's not just ad networks; if a news sites serves up stories based on your preferences, does that fall under "do not track"? Stay tuned, Mozilla said.

For more, see the Firefox 4 RC release notes; it's available for download on Mozilla's Web site.

This article, written by Chloe Albanesius, originally appeared on PCMag.com and is republished on Gear Live with the permission of Ziff Davis, Inc.