title: Add custom tooltip to row in DataGrid
body: <p>I would like to customize my DataGrid to show a tooltip within the selected row, please see the mockup images below for a better idea of what I want to achieve.</p>
  
  <p><strong>As it is at the moment</strong> - Shows a single selected row:
  <img src="https://i.stack.imgur.com/mW3lc.png" alt="enter image description here"></p>
  
  <p><strong>How I would like</strong> - Shows the same row selected, now with tooltip:</p>
  
  <p><img src="https://i.stack.imgur.com/OWv4K.png" alt="enter image description here"></p>
  
  <ul>
  <li>My DataGrid uses Binding to the ViewModel. </li>
  <li>Working with WPF &amp; C# for Windows desktop.</li>
  </ul>
  
  <p>I don't really have any idea how to achieve this, so I'm open to any suggestions at all.</p>