title: How to put a line after each grouping rows in a GridView?
body: <p>I am using a GridView that has many rows with the same values, so I grouped these rows using <a href="http://www.agrinei.com/gridviewhelper/gridviewhelper_en.htm" rel="nofollow noreferrer">GridViewHelper class</a>. Now I want to put a separate line between each grouping values. How to do that? </p>
  
  <p>The following snapshot shows you the current situation:
  <img src="https://i.stack.imgur.com/n4llO.png" alt="enter image description here"></p>