Android Question detect user input...

ok, i can't get exactly what i want so i need to try another approach. basically i want to know if the user is doing anything. i have detected the phone unlock with android.intent.action.USER_PRESENT. This is a start, but the phone may already be unlocked and the user is not there.

I know you can't trap keystrokes/screen input, so my question is this; are there any other ways to detect that the user is doing SOMETHING? I just need to know the user is present. The more ways the better.

Thanks.