I have now, thanks to you(r suggestion), but it doesn't show all the tabs/windows in one place. It only shows tabs of current window. Nor does it even show everything in a full new page. This add-on seems to be made only as a vertical tab bar as an alternative to the horizontal.
It has a quite impressive list of settings, but none of them enable the basic fundamental functionality I'm looking for.
I keep trying all the add-ons successively, although without success. I'd really appreciate a solution.