title: Clean messages in Windows Message Pump
body: <ol>
  <li>I don't know much about Windows Message Pump but I guess events are triggered using Message Pump.</li>
  </ol>
  <p>When my Web browser control navigates to some websites it fires various events of Document Completion. Once I have what I need in <em><strong>WebBrowser_Document_Completed()</strong></em> I want to ignore all further Document Completion.</p>
  <ol start="2">
  <li>How can I it?</li>
  </ol>
  <p>If I show a <em><strong>MessageBox()</strong></em> in <em><strong>Document_Completed(...)</strong></em>, It shows multiple message boxes, looks like it is running in parallel threads, but when I debug it I find that it runs always on main thread.</p>
  <ol start="3">
  <li>When are the other two threads created?</li>
  </ol>
  <p>Also, when I press Close it closes the window but the process is still running in the background. I am not using any other thread yet I still see two other threads when I debug.</p>