Conceivably Tech reports Mozilla is heading into a radical new direction with Firefox 5, this new browser is expected by the end of the first half of this year and may get pretty dramatic UI modifications:
According to the UI team notes, the browser interface is planned to be more responsive, there will be an updated URL bar (with a width of 240 pixels) and there will be substantial changes to the appearance and use of tabs.
First mockups show that Mozilla is thinking about what it calls a site-specific browser, which will dedicate tabs to specific sites, which will integrate a navigation menu and site links within a site tab. For example, a visit to Twitter would automatically integrate features such as new tweet, search or direct messages within the site tab. This is the first example where we see Mozilla attempting to deal with web applications, where it actually turns websites into apps, while the web browser remains the dominant access and visualization platform. The typical Windows shortcut to a website is also changed into an actual application icon.