On OS X 10.6 there is a button/lozenge on the right end of the title bar that toggles mini-mode when clicked. Apple removed this title bar button in OS X 10.7, so there is no longer a way to quickly toggle mini-mode with a single click. iTunes re-purposes the maximize (+) button to do this. Maybe Cog should do the same? Another option would be to add a toolbar button to toggle mini-mode. Finally, it would be nice to have an item in the main Window menu too so mini-mode toggle can be mapped to a hotkey with the system Keyboard Preferences.