Rated 2 out of 5 stars
seems, that i cannot edit my review, so here is a new one.
meanwhile, i found the button. (its next/left to the addressbar, where you can type in the URL)
unfortunately, the icon is very big and disperses the whole toolbar (no theme used),
and it is not possible to move the icon to an other toolbar!
(after ff-restart, it is placed at its origin position.)
the button does, what it should, but that doesnt give 5 stars. only 2 because of a bad ff-integration.