Opera has unveiled the first beta version of its latest desktop browser, Opera 11, which features a new way to organise tabs.

Traditionally tabs were opened side-by-side in the web browser, however, the latest version offers 'tab stacking' that allows user to put tabs on top of other tabs to ensure they are grouped by theme of site.

"Tab stacking reduces clutter and makes it easier to identify and work with sets of open tabs," Opera said.

To stack tabs simply drag one tab on top of another. Opera also said users can mouse over the stack to expand the group of tabs to identify them, while clicking the arrow icon expands the current stack across the tab bar.

"Because so many of us wrestle with tens or even hundreds of open tabs, we needed a way to simplify tab management. Just like stacking papers for future reference, stacking your tabs is an intuitive way to organise and collect your open web pages," said Jan Standal, vice president of desktop products at Opera.

Opera has also added extension support to the browser. According to the developer, in just three weeks (the time since the alpha release of the browser has been available for) 500,000 extensions, or add-ons that enhance the browser, have been downloaded. Furthermore, developers are adding between 10 and 20 new extensions every day. Extensions can be downloaded from Opera's dedicated web page.

Opera 11 also supports mouse gesture, which allows web browser to control the browser by moving their mouse, meanwhile the browser has been speeded up and its footprint reduced.

The beta version of Opera 11 can be downloaded now from Opera's website.