title: Popup control moves with parent
body: <p>Hopefully this is a quick one for you WPF experts out here.  Is there any easy XAML solution to allow my popup to move when the widow moves or changes size?  The code is below.  If not, I can always handle an event in the code behind.</p>
  
  <pre><code>&lt;Grid&gt;
      &lt;Canvas&gt;
          &lt;Expander Header="details" HorizontalAlignment="Center" VerticalAlignment="Top" ExpandDirection="Down"
                    Expanded="Expander_Expanded" Panel.ZIndex="99" Collapsed="Expander_Collapsed" Name="expander"&gt;
  
                  &lt;Popup PopupAnimation="Slide" Name="popup" Width="200" Height="200" StaysOpen="True" AllowsTransparency="True" 
                         IsOpen="False" &gt;
                  &lt;Grid Background="Cornsilk"&gt;
                      &lt;Grid.BitmapEffect&gt;
                          &lt;DropShadowBitmapEffect/&gt;
                      &lt;/Grid.BitmapEffect&gt;
                      &lt;Grid.RowDefinitions&gt;
                          &lt;RowDefinition Height="Auto"/&gt;
                      &lt;/Grid.RowDefinitions&gt;
                     &lt;TextBlock TextWrapping="Wrap" FontWeight="Bold"&gt;
                        Some example text
                     &lt;/TextBlock&gt;
                  &lt;/Grid&gt;
              &lt;/Popup&gt;
  
          &lt;/Expander&gt;
      &lt;/Canvas&gt;
  &lt;/Grid&gt;
  </code></pre>