title: Flutter TextField autocomplete overlay
body: <p>I am struggling to create TextField with autocomplete overlay. 
  I have form with TextFields and I want to display suggestions based on what is typed in TextField.</p>
  
  <p>Something like this:
  <a href="https://i.stack.imgur.com/Da2kv.png" rel="noreferrer">TextField autocomplete</a>
  I am not sure what the hierarchy of widgets should look like to achieve displaying the suggestions box above other widgets. Should I use Stack widget, OverflowBox widget or something else? </p>
  
  <p>Any help by hierarchy example appreciated.</p>