title: Multilevel column header for DataGrid in WPF
body: <p>I have a <code>DataGrid</code> which needs to look like this:</p>
  
  <p><img src="https://i.stack.imgur.com/jQBSU.png" alt="enter image description here"></p>
  
  <p>As you can see, there are multiple columns as well as multi-level column headers, some that span multiple columns.</p>
  
  <p>I need to do this in WPF, so kindly provide only XAML solutions which will create multi level column headers. </p>