Hi, new to the forums, new to my phone. I have a Droid 4.1.2. Rather than locking the device with the power button, I would like to be able to type a key on my slide-out keyboard that would simply make the screen go black without interfering with any running programs such as the camera or GPS. The same shortcut should restore the screen. Is there a free app that can do this? Thanks very much in advance. Looking forward to learning more.