title: WPF show "dummy" control until focused/clicked
body: <p>I have a list of heavy <code>Controls</code>, which I don't want to render before the user interacts with them (one at a time).
  I want to show a placeholder for each <code>Control</code> until the placeholder is clicked (preferably focused) and then render the real <code>Control</code>. </p>
  
  <p>What I've tried looks like this:</p>
  
  <pre><code>            &lt;ContentControl x:Name="theControl"&gt;
              &lt;TextBox x:Name="TextBlock" Text="Placeholder right here."/&gt;
              &lt;ContentControl.Style&gt;
                  &lt;Style TargetType="ContentControl"&gt;
                      &lt;Style.Triggers&gt;
                          &lt;DataTrigger Binding="{Binding IsFocused, ElementName=TextBlock}" Value="True"&gt;
                              &lt;Setter Property="Content" &gt;
                                  &lt;Setter.Value&gt;
                                      &lt;Grid x:Name="theGrid"&gt;
                                          &lt;Grid.ColumnDefinitions&gt;
                                              &lt;ColumnDefinition Width="Auto" SharedSizeGroup="CodeColumn"/&gt;
                                              &lt;ColumnDefinition Width="*"/&gt;
                                          &lt;/Grid.ColumnDefinitions&gt;
                                          &lt;TextBlock&gt;Heavy control part1&lt;/TextBlock&gt;
                                          &lt;TextBlock Grid.Column="1"&gt;heavy control part2&lt;/TextBlock&gt;
                                      &lt;/Grid&gt;
                                  &lt;/Setter.Value&gt;
                              &lt;/Setter&gt;
                          &lt;/DataTrigger&gt;
                      &lt;/Style.Triggers&gt;
                  &lt;/Style&gt;
              &lt;/ContentControl.Style&gt;
          &lt;/ContentControl&gt;
  </code></pre>
  
  <p>Anyone knows a better approach or what I'm missing?</p>