I don't know, that floating button in the top left bugs me in linux. It makes sense in windows because it just blends in with the tabs next to it, but in linux it's on its own line with the tabs showing up below it. The wasted space annoys me to the point that this is one of the main reasons why I do not use Firefox anymore.
I used to have the same problem, but it turns out that you can tell compiz to hide the title bar. Takes a tiny bit of getting used to (Alt is your friend), but it's pretty nice otherwise.
nxn messed up his or her pronouns. The "it" in "its own line with the tabs showing up below it" refers to the the title bar. It's that on Windows, the tabs and button take the place of the traditional title bar. On Linux, drawing in the title bar proved too difficult for a generalized approach that worked across window managers, so the title bar remains intact, and everything is offset by it.
