This means that in the intro menu the 'Quit' button immediatelly quits
and the 'Quit' in the menu of the normal game and scenario editor
immediatelly quits when the 'autosave_on_exit' patch is turned on.
This is the same way as the OS/window manager initiated quits, like
alt-F4 and the 'x' in the (OS/window manager drawn) title bar of OTTD.