It's a must-to-have!
Would it be possible to add an optional vertical scroll bar? Or a way to speed up scrolling using the mouse wheel (w/ a key modifier), at least? It may take ages to scroll from bottom to top tabs when there's a lot of tabs.

Initial testing is good. On first install, it doesn't look like to captures the current tree-state of the open tabs (may be my setup?).

Still to see if closing a tab in the intermediate tab stack loses the tab connections (may need 'Tab flip for Tree Style Tab'?).

Have tried the closing of an intermediate tab and it shrinks the tree, rather than remembering the call stack.

Exactly what I needed, thank you

Extremely helpfull Add-on. Helps in any kind of research or just by sorting the 20 tabs you have open. The only thing that is missing, is the option to save tabs with the hirachie. That would be super helpfull, if you want to continue your research later.