As you can see in the screenshot above, the Firefox folks are toying with the idea of a Google Chrome-like tabs-on-top interface.

n addition, Mozilla summarizes the pros and cons of the two designs very succinctly:

Positives:
- Save Vertical Space
- Efficiency/Remove Visual Complexity – Right now the tabs have to be connected to something. So we are adding an extra visual element for them to connect to.
- Shorter Mouse Distance to Page Controls

Negatives:
- Breaks Consistency/Familiarity – Moving things confuses existing users.
- Title is MIA – With the space removed from the titlebar you only get the truncated version in the tab.
- Longer Mouse Distance to Tabs – Takes longer to mouse to a tab.
- Lost Space – Sandwiched in between the application icon and the window widgets you lose some space.

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