title: Can't bind IsChecked on RadioButton with custom ControlTemplate
body: <p>I have been using a custom RadioButton control with a ToggleButton as the control template. Here's what the xaml looks like:</p>
  
  <pre><code>    &lt;RadioButton.Template&gt;
          &lt;ControlTemplate&gt;
              &lt;ToggleButton x:Name="tb" IsChecked="{Binding IsChecked, Mode=TwoWay, 
                                  RelativeSource={RelativeSource TemplatedParent}}" 
                                        Content="{TemplateBinding RadioButton.Content}"
                            PreviewMouseDown="tb_PreviewMouseDown"&gt;
              &lt;/ToggleButton&gt;
          &lt;/ControlTemplate&gt;
      &lt;/RadioButton.Template&gt;
  </code></pre>
  
  <p>It's been working well, except when I try to either programatically set a button's IsChecked property, or make a binding with it. Then the button that should be checked is visually unresponsive - it doesn't appear to be pressed, and the Aero mouse over effect does not appear. The Clicked event handler still works, and the IsChecked property of both the RadioButton and the ControlTemplate's toggle button are true when I examine their values. Amy I doing something wrong with the binding? Any ideas?</p>
  
  <p>Here's an example of how I use it in the application:</p>
  
  <pre><code>&lt;local:RadioToggleButton Content="1Hr" GroupName="Interval" x:Name="oneHrBtn" 
  IsChecked="{BindingPath=oneHrBtnIsChecked, Mode=TwoWay}" Margin="2 5 3 5" 
  IsEnabled="{Binding Path=oneHrBtnIsEnabled, Mode=TwoWay}"/&gt;
  </code></pre>