Rated 5 out of 5 stars

v0.7
I think You could set toolboxid attribute on TabsToolbar so it'll stay customizable outside toolbox.

And in the long run ... integrate groups with Tab Candy groups,

As mentioned in earlier review I love it.

This review is for a previous version of the add-on (0.6). 

Super great idea

Thanks a lot for the tip, I've implemented this and it will be in version 0.7!

It's definitly worth trying Rated 4 out of 5 stars

Since new Firefox brings fancy TabCandy interface and Vertical Tabs is aiming towards 4.0 release...
I think it's definitely good idea to go "close integration" road. And should benefit both Firefox (bring "useful" to all that candiness) and Vertical Tabs (nobody likes reimplemented features - TabCandy will bring groups to Firefox).
* all groups and tabs are displayed
* VarticalTabs groups == TabCandy groups
* DND tabs should add/remove/move between groups
* ect.

This review is for a previous version of the add-on (0.6).