Rated 4 out of 5 stars

Drag'n'drop is fixed in 0.9.3 version: https://addons.mozilla.org/ru/firefox/addon/vertical-tabs/versions/

Found @ http://twitter.com/#!/philikon/status/138361814072311809

This review is for a previous version of the add-on (0.9.1.1-signed.1-signed).