A continual annoyance: iTunes couldn’t be ideal-sized (resized to fit the width of my screen, exactly) like Mail.app. The solution? Hold down the option key when clicking the resize button.
Switching between laptop mode and laptop+external display now hurts less.
UPDATE: Turns out the option shortcut merely sizes your iTunes library window to fit the displayed columns, not to a maximized state. There are more people who think this is odd (even on Windows). A remnant of iTunes being a Carbon, and not Cocoa app?