title: Flutter Tabbarview underline color
body: <p>How to add underline to unselected tabs, like this:</p>
  
  <p><a href="https://ibb.co/mfkzKp" rel="noreferrer">https://ibb.co/mfkzKp</a></p>
  
  <p>Here you can see it is gray colour for unselected tabs, and blue for selected.</p>