title: Exception when trying to add Controls to a UserControl
body: <p>While I was trying to add Controls to my UserControl list it threw "The calling thread cannot access this object because a different thread owns it." exception.</p>
  
  <pre><code>        panel_PanelHolder.Children.Clear();
          panel_PanelHolder.Children.Add(usr_panel);
  </code></pre>
  
  <p>But when I used below code,</p>
  
  <pre><code>        Dispatcher.BeginInvoke(DispatcherPriority.Background, new Action(() =&gt;
          {
              panel_PanelHolder.Children.Clear();
              panel_PanelHolder.Children.Add(usr_panel);
          }));
  </code></pre>
  
  <p>It throws "Exception has been thrown by the target of an invocation." exception.</p>
  
  <p>What I need is to clear controls, and add a control to the panel. I'm not sure how to fix this ASAP. I'm using a STA thread to manipulate WPF window controls dynamically. Can someone help me on this? thx..</p>