Sticky immersive mode disabled after soft keyboard shown

Taken from this sample app by Google, you need to append this to the end of your activity, before the last end bracket:

@Override
public void onWindowFocusChanged(boolean hasFocus) {
    super.onWindowFocusChanged(hasFocus);
    // When the window loses focus (e.g. the action overflow is shown),
    // cancel any pending hide action. When the window gains focus,
    // hide the system UI.
    if (hasFocus) {
        delayedHide(300);
    } else {
        mHideHandler.removeMessages(0);
    }
}

private void hideSystemUI() {
    getWindow().getDecorView().setSystemUiVisibility(
        View.SYSTEM_UI_FLAG_LAYOUT_STABLE | 
        View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION | 
        View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | 
        View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | 
        View.SYSTEM_UI_FLAG_FULLSCREEN | 
        View.SYSTEM_UI_FLAG_LOW_PROFILE | 
        View.SYSTEM_UI_FLAG_IMMERSIVE
    );
}

private void showSystemUI() {
    getWindow().getDecorView().setSystemUiVisibility(
        View.SYSTEM_UI_FLAG_LAYOUT_STABLE | 
        View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION | 
        View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
    );
}

private final Handler mHideHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        hideSystemUI();
    }
};

private void delayedHide(int delayMillis) {
    mHideHandler.removeMessages(0);
    mHideHandler.sendEmptyMessageDelayed(0, delayMillis);
}

And you should be good. 🙂