Firefox 2.0 displays tab navigation buttons on each side of the tab strip when a lot of tabs are opened.
This scrolling feature can be disabled by just following a few simple steps.
1. Type about:config in the Firefox address bar and press Enter.
2. Now double-click on browser.tabs.tabMinWidth and change the value to 0.
Disabling the tab scrolling feature will cause Firefox to shrink the size of the tabs if too many of then are opened.