Probably the definitive tree tabs addon. Very customizable.

This add-on is almost perfect! the one thing im missing and hope you can work on it , is the possibilty to stick/pin tabs like normal tabs. I Know you can pin a tab but it moves to the top like an icon and doesnt stay in its horizontal view with its title.
An idea: to be possible to stick tabs in horizontal view like normal tabs and the possibility to add a custom name for it, so it can work like a Shortcut in list view.
(because to add it as a bookmark has another behaviour and envolves another panel)

Also if it could be possible to show all panels tabs in tree view (with their name and color) one under another to avoid having to click in each icon to access the panel and then the Tab.

Thanks a lot for your work!

loved it