title: Get DataGrid cell from mouse position
body: <p>I want to get the clicked cell of a <code>DataGrid</code> at the <code>MouseDown</code> event. So far I haven't been successful.<br>
  I tried</p>
  
  <ul>
  <li><p><code>dg.CurrentCell</code> - contains the previous clicked cell  </p></li>
  <li><p><code>dg.GetChildAt(...)</code> - doesn't work because the cells are not listed as children of the DataGrid</p></li>
  </ul>