title: how to filter more than once in Microsoft.Win32.OpenFileDialog()
body: <pre><code>    Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();
  dlg.FileName = "Document"; // Default file name
  dlg.DefaultExt = ".txt"; // Default file extension
  dlg.Filter = "Text documents (.txt)|*.txt"; // Filter files by extension here
  </code></pre>
  
  <p>I want to filter more than one type</p>