Rated 3 out of 5 stars
This works as it should as far as moving tabs is concerned. Very convenient actually. But I encountered the same problem with this as with the Write Area add-on - It disables all ability to customize the tool bars and reverts them to their default values. I would give further info and screenshots rather than post here, but I see no links to email you. I'll check back here if I remember.
I did not test it on my Windows 7 install. The bug happens in Ubuntu Linux 10.04 while using Firefox 4.0b4. This may be a bug exclusive to Linux, as other add-ons seem to only function correctly on Window while using the Firefox betas. (Tab Scope and the Office Black theme, for instance.)