title: BackgroundWorker thread must be STA
body: <p>I have a BackgroundWorker to call a function to do a long process at BackgroundWorker _DoWork, when error occur in the function I will prompt a customized messagebox:</p>
  
  <pre><code> WPFMessageBoxResult result = WPFMessageBox.Show("Activation Fail", "Error!!", WPFMessageBoxButtons.OK, WPFMessageBoxImage.Error);
  </code></pre>
  
  <p>The exception below happens at WPFMessageBoxResult class :</p>
  
  <pre><code>The calling thread must be STA, because many UI components require this. 
  </code></pre>
  
  <p>Thank you.</p>