Mozilla Firefox 4 Beta 2 released, with "App Tabs," persistent tabs that get you to your to favorite Web apps in an instant. App Tabs takes sites you always keep open—like Web mail or internet radio—and gives them a more permanent role in your browser. Every tab now has a "Make into App Tab" command in context menu, which shrinks the tab down to just the favicon and puts it on the leftmost position (similar to Chrome's pin tab feature). Also, tabs on top have arrived in Mac version.
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