Although it was nice when it did :) No, I am not that Mac OS fruitcake. XP, SP3. I think OSB went away when I upgraded FF from 14 to 19 (Won't go to 20 until Tab Utilities updates!) - it is supposed to be compatible through v.22, right?
Disabled/reenabled, even removed, redownloaded, reinstalled, retarted. The button does not even appear in the Customize table. The only sign that it exists at all on my machine is its listing in Addons.
One additional note - I use Vertical Toolbar, but it has never caused any problem before, and I really don't feel like messing around with it any more than I do FF20 as of yet.
Meanwhile I will try to find that other extension which I think I heard at least does away with that infernal docking!
Best Wishes.