I written a application that auto launch after system boot and with full screen window style, it is work fine after system boot and I manually unlock screen instantly, but if I do not unlock screen instantly, for example, wait for 10 seconds, the system status bar will overlay on my application. I think maybe system status bar launched before my app, so I set SystemClock.sleep(5000) after my app received system broadcast:BOOT_COMPLETED, but this is not useful.
You can now use Enterprise Home Screen to do this. EHS is an replacement home screen provided by Motorola Solutions.
EHS will allow you to disable the key guard completely and launch your application in a kiosk mode.