title: Expander content not visible
body: <p>I wanted to have an expander in my WPF application. It looks something like this.</p>
  
  <pre><code>&lt;Expander Header="Know Words" x:Name="expKnownWords" Margin="2,0,2,300" Height="30" IsExpanded="True" ExpandDirection="Down"&gt;
              &lt;Expander.Background&gt;
                  &lt;LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0"&gt;
                      &lt;GradientStop Color="Black" Offset="0"/&gt;
                      &lt;GradientStop Color="White" Offset="0.522"/&gt;
                  &lt;/LinearGradientBrush&gt;
              &lt;/Expander.Background&gt;
              &lt;StackPanel x:Name="pnlNextWord" Orientation="Horizontal" Height="200" Margin="10,20,10,20" VerticalAlignment="Top" Visibility="Visible"&gt;
                  &lt;TextBlock x:Name="txtWord" HorizontalAlignment="Left" Height="50" Width="200" Margin="30,100,50,100" VerticalAlignment="Center" Text="{Binding WordToShow, Source={StaticResource ReadWordsWindow}}" /&gt;
                  &lt;Button x:Name="btnShowMeaning" Margin="80,80,50,80" Height="30" Width="190" Visibility="{Binding ShowMeaningButtonVisibility, Source={StaticResource ReadWordsWindow}}" Content="{Binding LblShowMeaning, Mode=OneWay}"/&gt;
                  &lt;TextBlock x:Name="txtMeaning" Margin="20,100,50,100" Height="130" Width="300" HorizontalAlignment="Left" VerticalAlignment="Center" Visibility="{Binding MeaningVisibility}" Text="{Binding MeaningToShow, Source={StaticResource ReadWordsWindow}}"/&gt;
             &lt;/StackPanel&gt;   
   &lt;/Expander&gt;
  </code></pre>
  
  <p>Within the expander control, I need to have a stack panel which contains 2 textboxes and a button. The problem is that when I run the application nothing is visible under expander and I can't seem to figure out why?</p>