Excellent early bird, might do it on the long run. Rated 5 out of 5 stars

Thanks for bringing back Vertical Tabs to FF4.0b - you bring back the most wanted feature since 16:9 displays!
I can clearly understand the goal of staying bare of any options. Keep that goal, but...
yet, i'd also prefer to have them on the right side :) Is it impossible to integrate that choice to the general UI-"Customize..."r?
But, more important and as stated earlier, toolbar should definitely go to the top instead of bottom.
Also looking forward to App Tabs in a row at the top.

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