i was sitting in class and looked over at this girl who was texting on her phone.... but when i looked at the phone, it appeared to be off(the screen was black) and i asked her about it. she handed me the phone and it was fine. she told me she had something put on her phone so that people couldn't see what she was doing from a certain angle. can anyone help me figure out what it is? maybe a privacy screen or some kind of app?????????????