I have found the navigation bar now always show up ( or it does not auto hide after show up ). So anywhere I touch on the tablet, it is not in the correct position. I also note you already have a similar discussion on "Touch position lower than touch field"
There is an android call to hide the navigation bar:
View decorView = getWindow().getDecorView();
// Hide both the navigation bar and the status bar.
// SYSTEM_UI_FLAG_FULLSCREEN is only available on Android 4.1 and higher, but as
// a general rule, you should design your app to hide the status bar whenever you
// hide the navigation bar.
int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_FULLSCREEN;
Please see if that is useful to you or not.