title: Bind TextBlock in DataTemplate (resource) to Content of checked radio button
body: <p>I have a TextBlock in resource data template:</p>
  
  <pre><code>&lt;DataTemplate x:Key="MyDataTemplate" ItemsSource="{Binding MySource}"&gt;
      &lt;TextBlock x:Name="MyText" Text="{Binding ???}" /&gt;
  &lt;/DataTemplate&gt;
  </code></pre>
  
  <p>that I want to bind with <code>Content</code> of checked radio button:</p>
  
  <pre><code>&lt;RadioButton GroupName="MyGroup" Content="Code" /&gt;
  &lt;RadioButton GroupName="MyGroup" Content="Description" /&gt;
  </code></pre>
  
  <p>if Code radio button is selected, then I want the text become <code>Text={Binding Code}</code>.</p>
  
  <p>Please help, thank you.</p>