With more tabs than fit within the width of the tabs window, the arrows (<, >) will move to previous or next tabs, but stop short: they do not move to the first or last tab. This is new behavior with Firefox 14.

Also when the number of tabs is greater than will fit within the tabs line, creating a new tab doesn't change the display of the tabs line at all. Prior to Firefox 14 creating a new tab would always change the tabs line so that the newly-created tab was the rightmost of the tabs displayed on the tabs line.