I wouldn't trade tabs-on-top for anything. The single most common mouse action in a browser (or my browser, I should say) is to switch between tabs. In addition

I wouldn't trade tabs-on-top for anything. The single most common mouse action in a browser (or my browser, I should say) is to switch between tabs. In addition to the Fitts' Law benefit of having tabs on the edge, there's the ability to move the pointer smoothly from left to right on the tab bar without having to ever readjust up/down to hit the target tab.