Opera released the beta version of Opera 11 browser which supports Extensions and Tab stacking and many more features and improvements.

Features

Tab stacking - tab stacking lets you drag one tab over another to create a group.

Extensions support

Visual mouse gestures - This allows new users to discover the speed and power that mouse gestures offer.

A safer address field

Better performance

Enhanced HTML5 support

Extended auto-update

Plug-ins only on demand

Faster installation

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