Pressured on the innovation front from Google’s Chrome and Microsoft’s Internet Explorer 9, Mozilla dug deep and came out with a set of innovations that radically change world’s #2 browser. We have already reported about the imminent release of Firefox 4, the next iteration of the popular open source web browser. Here we will provide an overview of the most important changes added to the browser. Note that some of the described experiences may depend on the operating system. While we tried to explain such differences, do note that the article is written from the perspective of a Firefox 4 Beta/RC user on Windows 7 with Aero enabled.

Minimalism by Mozilla: Firefox 4 hides the traditional menu. If you still want to see it, press left "Alt" key on your keyboard
Minimalism by Mozilla: Firefox 4 hides the traditional menu. If you still want to see it, press left "Alt" key on your keyboard

On first glance you will notice some major changes to the interface. The new default interface moves the tabs on top of the address and search bar. The top menu will only consist of a prominent Firefox button in order to save as much space as possible for actual web content. When you hit the Alt-key, a traditional menu will be displayed. The address bar also received more space due to the removal of the reload, stop and home buttons to the left. The stop and reload buttons are right next to the address bar. While a page is loading a prominent red stop button marked with an X is displayed. Once the site finished loading, the button will turn into a reload button. The home button moved to the right of the search box.

The status bar has been removed, however a addon bar can be displayed at the users discretion. When you hover the cursor over a link it will still be displayed in an overlay in the down left corner (oddly when you have the search-text bar open, it will be displayed in the down right corner). Tab management also received some major changes. When you enter the URL or keywords of a website into the address bar that’s already opened, Firefox will suggest to jump to the respective tab instead of opening the site in a fresh tab.

For websites you have constantly opened, like social networks, webmail or the like, you can pin the tab as an app tab by rightclicking the tab and selecting the respective option. The tab will then be displayed at the left side of the tab bar. Whenever the content in the pinned tab changes, it will be subtly highlighted to notify you about new tweets, wall posts, mails or whatever you have pinned up there. The important thing about this feature is that the tab will only be displayed by the icon of the website and the pinned tabs are always visible regardless of how many tabs are opened or which tab group you are currently in.

This brings us to the next feature ? tab groups. The feature has been developed under the name of Tab Candy and provides an overview of all the opened tabs in the browser. Per default there is only one tab group, though the user can create different tab groups and move tabs via drag and drop from one group to another. The size of the tab preview depends on the available space. Firefox will automatically decide on the size and arrangement of the tabs in the group. If the tab group is sized very small, the tabs will be displayed as a stack of sites where only a preview of the topmost tab is displayed.

There are also some major changes under the hood. Firefox 4 uses a new JavaScript engine dubbed JägerMonkey. It combines the previous tracing mechanism with a JIT compilation technique that jumps in whenever the previous method fails to provide performance gains. This allows Firefox to compete on JavaScript benchmarks again. On top of that the JavaScript heap is now managed in compartments, meaning that JS objects of each website get their own heap as opposed to one single large heap for all websites.

The big buzzword among current generation browsers is hardware acceleration. The competition added it to their latest browsers so Mozilla followed suit and is now able to provide that as well. Even under Windows XP Mozilla tries to provide some level of hardware acceleration. Contrary to Microsoft’s Internet Explorer 9 the open source browser will continue to support Windows 2000 and upwards. Some features are only available on later generations of Windows, namely Vista and 7. In Firefox both content acceleration and compositing acceleration are used. The former will not be available on Windows XP as there is no suitable API available. The latter is based on Direct3D on Windows, so even XP users will get it. Some people object to the quality of font rendering with Direct2D content acceleration enabled. To be fair it should be stated that IE9 is affected by this as well. As a longtime user of the beta I can only say that in the beginning it is irritating but over time you’ll get used to it. That really can be said about a lot of the new features.

When talking about hardware acceleration we really should mention WebGL. WebGL is a 3D interface for browsers based on OpenGL ES 2.0, which is a subset of the full OpenGL. Some impressive demos can be seen at Mozilla. Google has implemented a WebGL-based browser of the human body. At the moment WebGL is not supported by Microsoft?s Internet Explorer. For Opera and Safari there are at least development versions that have added support for it. Once the technology gets broader support, I’m sure we will see a lot more WebGL use in actual websites apart from demos. [at BSN*, we’re working on using the API].

GPU-accelerated 3D inside a browser: WebGL really works!
GPU-accelerated 3D inside a browser: WebGL really works!

HTML5 support has also been vastly improved. The new web standard is still a little bit volatile in some parts, but the most current versions of different web browsers already support a good deal of the features. One disputed HTML5 feature is the video tag. In Firefox only WebM video is supported out of the box, while support for other codecs like H.264 can be added via plugins. The same is true for Google Chrome, while Microsoft and Apple support H.264 and don’t include WebM. The advantages and disadvantages of each of these formats can make an article of their own, but it’s something that should be known about the feature sets of the respective browsers.

If you use Firefox on different computers and mobile devices you should probably give Firefox Sync a try. Firefox Sync provides cloud-based storage of history, bookmarks, tabs and passwords. All that is required is to sign up for an account at Mozilla and set it up in the Firefox config. The process is detailed on the Sync website. For mobile devices it is either advised to use Firefox Mobile. For iOS devices Mozilla provides Firefox Home which syncs history, bookmarks and open tabs via your Sync account.

The new release of Firefox includes a lot of other changes as well. For example the addon manager has been redesigned. Also Firefox now supports a new addon API dubbed JetPack that should be stable over future browser versions. This should help keep addons compatible with future updates to the browser. Talking about updates, Mozilla wants to change the development cycle of Firefox in the future. Firefox 4 took very long to be completed and end users had to wait quite long to get all the new features in a release version. Future releases should focus on smaller changes and will be released more often in order to bring new features more quickly to users.

Detailing every change in this article would go a bit too far – we tried to focus on the most notable ones which really affect daily use. The full list of changes can be seen at the Mozilla website.