Seems to be a reasonable substitute for the XUL-version. An absolutely essental addon for firefox!
But I like to report a bug. When I click on a tab and drag it to another window, the tab disappears from the source window (as expected), but does not reappear in the destination window. First you believe that it has been erased, but turning off the sidebar by clicking the show menu, and the turning it on again makes the moved tab magically reappear.
I hope you can fix this soon, since it is very confusing..