title: How can I load a WPF (xaml) window inside of another WPF windows in a Panel?
body: <p>Is this possible?</p>
  
  <p>I used a Frame control and:
  show(ex:showwindow.xaml)</p>
  
  <p>But I get this error:</p>
  
  <blockquote>
    <p>root element is not valid for navigation</p>
  </blockquote>