I turned on tabbed browsing at some point while using Safari to try it out. Turns out I hate it. Keyboard shortcuts are much easier and faster for me. (Yay for Command-`).
But when I turned it off, Safari began to open each new window one size shorter, instead of the same size. I always keep my browsers filling the screen, and since that is not what the + button does to Safari, I have to drag the resize box every time I open a new window, which means using the mouse way too much. Is there some file somewhere where I can change this preference back to what it was?