Capturas de pantalla
Sobre esta extensión
Hide the tab bar if there is only one tab. I don't know why Mozilla changed their code to show the title bar if tabs are not there in version 29 and above. So far I do not see an easy way to change it, but you only lose about 5 pixels verse if it was hidden. It's probably more useful that way anyway since you get the title of the page you are on.