I don't want to do advertisement but sample app for behavior of my application is ESET antivirus.
One requested feature of my application is that for uninstall is needed password. I add my app to device admin list and it is not possible to uninstall it now. But you can Deactive app as admin device. Whan you go to Settings > Location & security > Select device administrators and you try to deactive ESET Security it starts the activity (I guess from DeviceAdminReceiver.onDisableRequested()) which is waiting for password and your mobile is locked. Home button, back button and even SwitchOff button doesn't react=>
How it is possible that Home,Back,SwitchOff and Camera button doesn't react?
EDIT - second question removed (After I took out battery from my phone - ESET wasn't device admin too)
Thank you for ideas.