I have an idea of an app - sort of. I would call it StealthMode. Idea is that it would be a theme that would change the desktop black as well as lockscreen and the desktop would be without apps. So nothing could be seen if you try to unlock the phone and nothing either if you get to desktop. For the top bar to be shown or the application page you would need to use some certain keys so that hitting the upper corner or the top of the screen would not bring anything to screen except open apps. When you would install the app and launch it you would make shortcuts to number keys. The app should make it to be able to launch apps by typing the apps name or using shortcuts and pressing enter. After one saves the settings in the app you would launch the stealth mode by typing StealthMode and pressing enter. In the lock screen you should also be able to give passcode with keys and pressing enter. If you would want to be exposed again you would type ExposeMe and press enter. The apps would work normal and show the top bar and other stuff normally.