title: how to get the x:name in datatemplate
body: <p>I'm setting the grid in the datatemplate.And i need to add some ellipse in this grid by code,because the amount of ellipse is dynamic setting the grid in the datatemplate.
  I also try to add grid and ellipse by code,and add to the datatemplate,but i can't find the visualtree </p>
  
  <pre><code>&lt;syncfusion:LineSeries.TooltipTemplate&gt;
                                  &lt;DataTemplate  x:Name="pupmadata"&gt;
                                      &lt;Border x:Name="PumpAtooltip" Height="72"  BorderBrush="#ff00ffff" BorderThickness="1,1,1,1" Background="#FF0B0F3C"&gt;
                                          &lt;StackPanel Orientation="Horizontal"&gt;
                                              &lt;Grid  x:Name="pu"&gt;
                                              &lt;/Grid&gt;
                                          &lt;/StackPanel&gt;
                                      &lt;/Border&gt;
                                  &lt;/DataTemplate&gt;
                              &lt;/syncfusion:LineSeries.TooltipTemplate&gt;
  </code></pre>