Update: First off thanks for the comments. Looks like I missed something, like the fact that I was running Firefox 7 Nightly maximized. Normally I only have the browser window only partial of the screen-width. But this does bring up an interesting question, why not have everything on one row even if the browser window is not maximized? The first screenshot while a partial screen size, is almost 800 pixels wide which would be for those running 800×600 would be maximized. Just seems like wasted space in that title bar.
While I was trying out the different versions of Firefox to see which ones would allow me to add toolbar icons next to the tab bar, I noticed a slight change on the UI in Firefox 7. The Firefox (or in this case Nightly) button has been placed to the left of the tab bar. Currently the Firefox button is by itself up in the underutilized title bar in Firefox 4, 5 and 6.
Below is from Firefox 7 Nightly. Tabs have been shifted up and to the right of the ‘button’. Further the Minimize, Maximize and Close (window) buttons are now to the right of the tab bar.
Have to admit this is a nice change as there is a lot of wasted space currently between the ‘button’ and the window buttons. I suppose this was Mozilla’s solution to no longer using the title bar to display the title of the current tab. Interestingly though, I took a look at IE9, Chrome and even Opera all of them still have the window buttons by themselves on the title bar and like Firefox they don’t make use of the title bar (except Opera which does display the current tab’s page title in the title bar).