Widget demo - How come the tab bar stays on screen ?

I am having a play with the widget demo trying to learn tab bars and composer. I noticed the tab bar is only created in main and doesn’t disappear when other scenes are displayed, at first I thought they where overlay scenes but they are not.

Is this because the tab bar is not associated with Composer and/or screen groups and hence doesn’t get overwritten on screen ?

I presume as long as you don’t put anything on that part of the screen you are fine ?

Dave