The way Opera handles it is better, Firefox has always done it backwards.
In Opera, think of the tabs bar as the windows taskbar with each tab representing a seperate browser window complete with it’s individual navigation and address bar.
You can do one thing.Moove the tab bar to the bottom of the window.I personally prefer it because it somehow feels like another taskbar.You can controll the opera tabs and the windows without having to moove the mouse a long way to the top of the screen.
To moove the tab bar to the bottom,right click on it and select 'customize',from the drop-down menu adjascent to 'placement' select 'bottom'.
You can keep anttoolbar on any edge of the screen this way.