title: Application.Current.Shutdown(); is defined in an assembly not referenced
body: <p>I'm getting the error: </p>
  
  <blockquote>
    <p>Error 1   The type 'System.Windows.Markup.IQueryAmbient' is defined in
    an assembly that is not referenced. You must add a reference to
    assembly 'System.Xaml, Version=4.0.0.0, Culture=neutral,
    PublicKeyToken=b77a5c561934e089'.</p>
  </blockquote>
  
  <p>When doing the following:</p>
  
  <pre><code>public void ExitApplication()
  {
      Application.Current.Shutdown();
  }
  </code></pre>
  
  <p>The project is targeted to .NET 4.0, my Visual Studio is 2010, I tried adding </p>
  
  <p><code>using System.Windows.Markup;</code> with no succes, and</p>
  
  <p><code>using System.Xaml;</code> where Xaml doesn't exist in namespace System.</p>
  
  <p>What should I do  to fix this?</p>