title: Modeless Qt window on top of parent, but not on top of other applications
body: <p>I wish to have a Qt dialog window that:</p>
  
  <ol>
  <li>always stays on top of its parent (the main application window),</li>
  <li>allows the user to interact with the parent window, and </li>
  <li>does not always stay on top of other applications.</li>
  </ol>
  
  <p>I've been able to achieve 1 and 3 by making the dialog modal, and I can achieve 1 and 2 by using the Qt::WindowStaysOnTopHint window flag.  But I cannot manage to make all three work - is it possible?</p>
  
  <p>In case answers are OS-specific, I mainly work on a Mac, but I would prefer a solution that also applies to Windows and Linux.  Thanks!</p>