title: User control in Data template not shown
body: <p>I have this ComboBox</p>
  <pre><code>&lt;ComboBox x:Name=&quot;Renderer&quot; ItemsSource=&quot;{Binding RendererItems}&quot; 
        ItemTemplate=&quot;{StaticResource DropDownItemTemplate}&quot; SelectedIndex=&quot;0&quot;&gt;
        &lt;i:Interaction.Triggers&gt;
            &lt;i:EventTrigger EventName=&quot;SelectionChanged&quot;&gt;
              &lt;ei:CallMethodAction TargetObject=&quot;{Binding}&quot; 
               MethodName=&quot;RendererItemsSelectionChanged&quot;/&gt;                               
            &lt;/i:EventTrigger&gt;
        &lt;/i:Interaction.Triggers&gt;
  &lt;/ComboBox&gt;
  </code></pre>
  <p>And this Data Template for the items</p>
  <pre><code>        &lt;DataTemplate x:Key=&quot;DropDownItemTemplate&quot;&gt;
              &lt;StackPanel Orientation=&quot;Horizontal&quot;&gt;
                  &lt;UserControl Content=&quot;{Binding Icon}&quot; Width=&quot;24&quot; Height=&quot;24&quot;/&gt;
                  &lt;TextBlock Text=&quot;{Binding Text}&quot; VerticalAlignment=&quot;Center&quot; HorizontalAlignment=&quot;Left&quot; Margin=&quot;10,0&quot;/&gt;
              &lt;/StackPanel&gt;
          &lt;/DataTemplate&gt;
  </code></pre>
  <p>And the data comes from:</p>
  <pre><code>public ObservableCollection&lt;ComboBoxItemModel&gt; RendererItems { get; set; } = new ObservableCollection&lt;ComboBoxItemModel&gt;();
          public MainWindowViewModel()
          {
              RendererItems.Add(new ComboBoxItemModel() { Icon = new RenderedIcon(), Text = &quot;Rendered&quot; });
              RendererItems.Add(new ComboBoxItemModel() { Icon = new WireframeIcon(), Text = &quot;Wireframe&quot; });
              RendererItems.Add(new ComboBoxItemModel() { Icon = new ShadedIcon(), Text = &quot;Shaded&quot; });
              RendererItems.Add(new ComboBoxItemModel() { Icon = new HiddenLinesIcon(), Text = &quot;Hidden Lines&quot; });
          }
  </code></pre>
  <p>The ComboBoxItemModel class is defined like this:</p>
  <pre><code>    public class ComboBoxItemModel
      {
          public UserControl Icon { get; set; }
          public string Text { get; set; }        
      }
  </code></pre>
  <p>The first time that I click on the Combo is shown like this:</p>
  <p><a href="https://i.stack.imgur.com/z7Vi2.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/z7Vi2.png" alt="enter image description here" /></a></p>
  <p>As you can see the selected item have no Icon</p>
  <p>The second time that I click on the Combo is shown like this:</p>
  <p><a href="https://i.stack.imgur.com/EzxRj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EzxRj.png" alt="enter image description here" /></a></p>
  <p>Now the item that I have selected have no Icon. But I want that Combo items <strong>always</strong> have an Icon.</p>