A have a small suggestion for more intuitive UI.
When I click the mouse middle button on any link, it will open in a new tab. When I click it on back/forward it open its in a new tab. It is a great set-up that i use all the time, but following the same logic I would expect that such click on a tab will dupplicate it - it closes it instead.
Could you please make the dupplication a new default behaviour? O:-)