I was playfully clicking the browser while thinking about something and I found a neat short cut for Mozilla Firebird!
If you want to close a tab click the middle button in the mouse. And if you want open a new tab focus the mouse on unoccupied space between the tabs and the close button and Double click the middle button and voila a new tab! cool is it not 😉
(There you go I said it! I qualified Firebird with Mozilla.. hope that makes some of you happy!)