Exit Application Button

It's useful to give end-users a way to exit a full-screen application. In the event something goes awry, they can close Rho (or right now, PocketBrowser) and re-launch it. Right now, I'm doing this by placing a "hot spot" in the upper-right corner of the application that closes the app.

Is there a better way that other folks have implemented to accomplish this that isn't so easily accessed by the general public? I suppose I could prompt the user for a password upon pressing the hotspot, but that seems like overkill.