You say :
“USAGE : Access the popup menu by clicking on the Tabzen logo on the toolbar, to the right of the address bar. The menu lists the open tabs and windows.”
Instead of the list of all tabs, only the current tab appears.
I have to click on the gear wheel on top right to see all open tabs and folders I created.
When I created a first folder "VPN ", all tabs ended up in it.
I had to move these tabs to the root, but some are duplicated.
In short, I'm waiting for this extension to be ready before reinstalling it.