this add-on is a very good replacement for onetab. I like it won't delete the saved tab after I open it. It works more like a bookmark.
Few suggestions:
1. instead of a short cut, we need a button to save all tabs. I think you can put it on the end of tabzen's dropdown menu.

2. similarly, a button to open tab manager in dropdown menu.

3. a function of opening all saved tab in a folder

4. the user interface of tab manger is functional, but not particularly aesthetically appealing (in comparison, I think Tobi is quite good in terms of its UI).