title: how to change the color of the circle inside radio button
body: <p>I want to change only the color inside the radio button when clicked. I mean the tiny dot inside the circle.</p>
  
  <p>How in WPF can i do this?</p>
  
  <p>I tried this code but it is saying the content is set more than once</p>
  
  <pre><code>&lt;BulletDecorator Background="Transparent"&gt;
      &lt;BulletDecorator.Bullet&gt;
          &lt;StackPanel Orientation="Horizontal"&gt;
              &lt;Grid Width="40" Height="40"&gt;
                  &lt;Ellipse Name="MainEllipse" Width="40" Height="40"&gt;
                      &lt;Ellipse.Fill&gt;
                          &lt;LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0"&gt;
                              &lt;GradientStop Color="#FFC8C8C8" Offset="0" /&gt;
                              &lt;GradientStop Color="#FFF7F7F7" Offset="0.991" /&gt;
                          &lt;/LinearGradientBrush&gt;
                      &lt;/Ellipse.Fill&gt;
                  &lt;/Ellipse&gt;
  
                  &lt;Ellipse Margin="10,10,10,10"
                           Fill="#C0C0C0"
                           Width="Auto"
                           Height="Auto" /&gt;
  
                  &lt;Ellipse x:Name="Selected"
                           Margin="10,10,10,10"
                           Width="Auto"
                           Height="Auto"&gt;
  
                      &lt;Ellipse.Fill&gt;
                          &lt;SolidColorBrush Color="Navy" /&gt;
                      &lt;/Ellipse.Fill&gt; 
                  &lt;/Ellipse&gt;
              &lt;/Grid&gt;
              &lt;ContentPresenter Margin="5,0,0,0" VerticalAlignment="Center" /&gt;
          &lt;/StackPanel&gt;
      &lt;/BulletDecorator.Bullet&gt;
  &lt;/BulletDecorator&gt;
  </code></pre>
  
  <p>Thanks in advance,</p>
  
  <p>John.</p>