For my money, dragging to the top doesn't work at all. It will park there, but only for the full width of the VS window. If you have your projects folder on the side, the file tabs will extend over that as well as the editor window area, which makes no sense.
I have suggested elsewhere that the filetabs window should be replaced (except for those who love it, of course) by an enhancement to the Editor Pane that would incorporate the tabs in the pane itself. Top, bottom, side, whatever. I haven't heard any comment on that suggestion, but for now I seem to be stuck with tabs at the bottom.
(I'd b e happy to stand corrected if I've missed something.)