title: wpf style ,how to reference border's borderbrush to background
body: <p>there is a border ,and i want to change it's border color and background color at the same time.
  so , i define a style bellow</p>
  
  <pre><code>&lt;Style x:Key="EoE" TargetType="{x:Type Border}"&gt;
  &lt;Setter Property="BorderBrush" Value="{StaticResource LightGreen}"/&gt;
  &lt;Setter Property="Background"&gt;
      &lt;Setter.Value&gt;
          &lt;SolidColorBrush Color="{Binding Path=BorderBrush }"  Opacity="1"/&gt; 
      &lt;/Setter.Value&gt;
  &lt;/Setter&gt;
  &lt;Setter Property="Effect"&gt;
      &lt;Setter.Value&gt;
          &lt;DropShadowEffect ShadowDepth="0" Color="White"  Opacity="0.5" BlurRadius="10"/&gt;
          &lt;!--&lt;BlurEffect Radius="3" RenderingBias="Quality"/&gt;--&gt;
      &lt;/Setter.Value&gt;
  &lt;/Setter&gt;
  &lt;Setter Property="BorderThickness" Value="2"&gt;&lt;/Setter&gt;
  </code></pre>
  
  <p></p>
  
  <p>what i want to change at runtime is the borderbrush ,then i want the background solidcolorbrush changes at same time .</p>