title: Grid.GetRow and Grid.GetColumn keep returning 0
body: <p>I have a 10x10 <code>Grid</code>. And in each space I have added a label to which I added a mousedoubleclick event handler. So when I double click the label it's supposed to show the <code>Row</code> and <code>Column</code> number, but I only get 0 for both properties. </p>
  
  <p>This is the code... (and yes I have set <code>Grid.SetRow</code> and <code>Grid.SetColumn</code> for each label)</p>
  
  <pre><code>private void grid_Checked(object sender, MouseButtonEventArgs e)
  {
      MessageBox.Show(Grid.GetRow(e.Source as UIElement).ToString());
  }
  </code></pre>