title: Create buttons with negative border radius and align them in Flutter
body: <p>I want to build a layout like this </p>
  
  <p><a href="https://i.stack.imgur.com/EVk39.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EVk39.png" alt="enter image description here"></a></p>
  
  <p>Where the two external elements are buttons, while the inner one is a TextField.</p>
  
  <p>How can I create a layout like this in Flutter? </p>
  
  <p>My idea was to use absolute positions to align the left side of each element and to use elevation to handle overlapping but I'm not sure it's the best way and I don't know how to create the buttons.</p>