title: How to make row expandable and collapsible in datagridview
body: <p>I want to make <code>DataGridView</code> in which there are so many <code>Groups</code> and <code>SubGroups</code> and I want to make <code>Row</code> expandable and collapsible. Like if 'A' is a <code>Group</code>, in which three <code>SubGroups</code> values 'xxx', 'yyy','zzz' when I expnad 'A' <code>Row</code> then these <code>SubGroups</code> should show and when collapse 'A' <code>Row</code> <code>Subgroups</code>should hidden.
  Like this image</p>
  
  <p><img src="https://i.stack.imgur.com/0nIAB.png" alt="enter image description here"></p>