Pressing power button both turns off the screen (even if some application holding wakelock) and stops receiving input from it.
How to stop receiving input (and require password to get into normal mode again), but still show what is the foreground application displaying, like "view only" mode.
Example scenario:
- I open compass application;
- I use that "lock, but not hide" thing;
- Now touching the screen just does nothing, but the application is still updating things on it;
- I press power button (unlock);
- It asks to slide for unlock and/or password;
- Unlocked.