how to get android system bottom keys back?

Question

I'm developing an android app that blocks incoming phone calls while running.

but after a block sequence android's main keys(Back,Home,..) just changes to a dotted circle !

can any one please tell me what is this

and help me to get main buttons back?

by the way - i'm testing on : Sony C2305(Android 4.2.2)

Answer 1

This is what happens when your android phone is ringing(in default). since you changed default functionality of androids caller mechanism so its what really happen:

1- your phone rings and default caller turns on and hides android system keys in order to display caller screen
2- your application launches too and rejects call using code(and not androids caller application)
3- so as call rejected so androids default application closed with no response(without getting KEYs back!) Thats it. so i guess you should work with main caller istead of your own code to solve this problem.

Hope help you