title: My ElevatedButton not working in StackWidget. FLUTTER
body: <p>I'm trying use IndexStack in my app. But I have a problem with <strong>Stack</strong> and <strong>ElevatedButton</strong>. I trying press button and it don't response anything to me. But the blue button bellow is still working well
  Thank for concern about my issue.</p>
  <p><strong>Codepen:</strong> https://codepen.io/sucanabo/pen/xxqPrRw</p>