title: How to obtain the PIDL of an IShellFolder
body: <p>If I have an <code>IShellFolder</code> interface pointer. How might I obtain its PIDL?  </p>
  
  <p>I can see how to enumerate its children, and I can see how to use it to compare any two children. But how might I get its own pidl?</p>
  
  <p>I ask because I'd like to know: </p>
  
  <blockquote>
    <p>Is this IShellFolder == Another IShellFolder</p>
  </blockquote>
  
  <p>I can use <code>IShellFolder::CompareIDs()</code>, but I have to have the IDs of both folders.</p>