kakajika

class FullscreenOverlayService extends Service {

    private View overlay;
    private WindowManager windowManager;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

Kozlov-V

final WindowManager.LayoutParams params = new WindowManager.LayoutParams(
WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN,
PixelFormat.TRANSLUCENT);

WindowManager wm = (WindowManager) getApplicationContext()
    .getSystemService(Context.WINDOW_SERVICE);