Doubleclick not duplicate Rated 5 out of 5 stars

I'm using the penultimate 1.12 version in and this feature doesn't work. Is this only available for the 3.0 version? Is it possible to be available for 2.0?
Otherwise, very fine in Default theme. Especially like the expansive tabs and adjustable tabbar.

Requested Feature: If at all possible, a toggle button between default tabbar and vertical would be useful. With only a few tabs open, the default tabbar works fine. With many tabs open, vertical tabs are best.