I really liked the original Panorama that shipped with Firefox. This add-on is a great attempt at restoring this feature.
One big problem I've found with this version (and I don't remember if it was a problem with the original Panorama) is if you transfer a tab from one window to a window that has Panorama grouped tabs then the add-on GUI can't see the newly dropped in tab. They are still there just hidden, and you can't manage them. I'd have thought the desired behaviour would be to drop the tab into the currently open Panorama Group.

I was looking an extension like the old Showcase. Unfortunately not the same. The tab are too small and I cannot organize them as I want mainly in term of size

Расширение, в принципе, удовлетворяет моей необходимости, но группы не сохраняются между перезапусками.
Закрываю/открываю FF, все группы пропадают и все разгруппированные вкладки сваливаются обратно в одну группу. 2 раза уже так проделал. В первый раз думал, что просто глюк.
И насчёт сохранения резервной копии. Сохранил, а как восстановить из неё?
Плюс, В резервной копии сохраняются вкладки только одного окна или всех?

A nice alternative for Tab Groups, Thank you for it!

But with some little Bugs. From time to time there's some unexpected behaviour:
- All Tabs are in one group, all other groups are gone. Or
- All groups are still there but the tabs are gathered in one group (maybe the last that was opened). Or
- The last letter of every group name is gone.
Or a combination.

I'm curious about what happend next ;-)

Best replace for native tabs groups in FF. BUT have a fatal bug - does not always save pinnet tabs when you open a new group.