The firefox-stable ppa has builds only for maverick and lucid.The firefox-next has builds for maverick, lucid and karmic.
If you are using an older version of Ubuntu, then download FF 4 from Mozilla and install it manually. See instructions on my web site:
Chrome does that, but is the only application I have installed which does not behave correctly. I use KDE, which has lots of cool features related to window management, but with Chrome is a complete mess. For instance, I can't double-click on the title bar to collapse the window. It maximizes instead, which is really annoying. So in my opinion, the decision of Mozilla to not mess with the window title bar was a good one.