title: how to prevent WPF MediaKit MediaClosed fired
body: <p>I have a WPF window, there is a <code>ContentPresenter</code> inside it, and two User Controls (one host <code>MediaUriElement</code>, the other host other things) and two buttons (to switch between User Controls).</p>
  
  <p>When I switch to <code>MediaUriElement</code> User Control, I assign a video Uri to it, and the video play very well, then I switch to the other User Control, at this time, the <code>MediaClosed</code> event fired, when I switch back, the video cannot be played.</p>
  
  <p>I want the video can be played from the beginning or continue play at last switch away, How shall I do?</p>
  
  <p>Very appreciated for any help.</p>