title: Flutter - SingleChildScrollView fixed widget
body: <p>there is an ability to have a SingleChildScrollView into a Scaffold that have another widget over the SingleChildScrollView that does not need to be scrolled.
  For example I've a SingleChildScrollView and I need to add a fixed button into a specified position, but this button does not to be scrolled.</p>
  
  <p>I try with a Stack widget but if I add a button widget before the SingleChildScrollView this is not be able to be clicked otherwise if I add the button after the SingleChildScrollView the scroll touch does not work.</p>
  
  <p>Anyone have some problem?</p>