22 March 2011, 17:40

What's new in Firefox 4.0

by Christopher von Eitzen

After more than a year of development and months of delays, the final version of the Firefox 4.0 web browser has arrived. Based on the latest Gecko rendering platform, it adds a range of improvements and new features over the previous 3.6.x branch.

As previously announced, the Mozilla Project has released the final version of Firefox 4, the non-profit organisation's next generation web browser based on version 2.0 of the Gecko rendering platform (the Firefox 3.6 branch uses Gecko 1.9.2). This major update to the open source browser arrives after more than a year of development which included twelve beta releases and two release candidates, as well as a number of delays which postponed the arrival of the final version.

Firefox 4.0 includes a new "Tabs On Top" layout across all platforms. Firefox 4 features a range of improvements and new features aimed at both users and developers alike. Once installed, Firefox 3.x users will immediately notice a new default 'tabs on top' layout across all platforms – on Windows 7 and Vista systems, the Firefox button also has a new look and support for Aero Glass has been added. With the new Tab Groups feature, also known as "Panorama", users can better manage their tabs by zooming out of the current browser tab to view a grid of thumbnail images for each open tab.

The stop and reload buttons have now been merged into a single button and the new Bookmarks Button has replaced the Bookmarks Toolbar. However, the developers note that users can "switch it (the Bookmarks Toolbar) back if you'd like". Additionally, users can now turn any browser tab into an "App Tab" by right-clicking on it and selecting "Make into App Tab" from the context menu. The Firefox Start Page (about:home) has also had its design refreshed.

Windows and Linux versions of Firefox 4.0 include a new Firefox Button which contains all of the menu items.
Source: Mozilla Under the hood improvements include a new JavaScript engine called JägerMonkey that is up to six times faster than that used by Firefox 3.6, and built-in Direct2D Hardware Acceleration for Windows 7 users which takes advantage of users' built-in graphics hardware – the GPU – on Windows systems using DirectX 10 to improve overall graphics performance; this allows the browser to load and display graphically intensive websites even faster. Some graphics rendering operations are now also hardware-accelerated using Direct3D 9 on Windows XP, Direct3D 10 on Windows 7 and Vista, and using OpenGL on Mac OS X. According to the developers, OpenGL support for Linux will arrive in a future release. On Mac OS X systems, the browser takes advantage of the Core Animation rendering model for plugins helping them to be drawn even faster and more efficiently.

Support for Firefox Sync is now built-into the browser. Previously only available as an add-on, support for Firefox Sync is now built-in, allowing users to synchronise their bookmarks, passwords, preferences, forms, history and open tabs between Firefox installations running on different PCs or on mobile devices. The new Add-ons Manger (about:addons) now appears in a new browser tab instead of a separate window and some add-ons can be installed without restarting the browser, as well as automatically updated in the background.

Thanks to an overhaul of the bookmarks and history code
The Firefox 4 Add-ons Manager now appears in a new tab instead of a separate window. , startup and bookmarking performance have been improved and, with the Smart Location Bar, users can search for and switch to already open tabs. The developers have added support for the "Do Not Track" (DNT) header, an option that users can enable via a check box under the "Advanced" tab in Firefox's Preferences, to signal websites that the user wishes to opt-out of online behavioural tracking.