title: Screen events in Caliburn Micro (showing message box at startup)
body: <p>I want to show message box on app start.<br>
  I used <code>OnActivated</code> method of my first screen to show modal dialog.</p>
  
  <p>It worked fine. And the case when user deactivated app without pressing Ok worked fine. After activating app again new <code>messageBox</code> was shown. Perfect.</p>
  
  <p>But issue was that app wasn't completely initialized and OS killed app after 5 or 10 sec of waiting. </p>
  
  <p>I tried to use <code>OnViewLoaded</code> event. But this event doesn't fire every time screen is <code>navigatedTo</code>.</p>
  
  <p>Can i somehow get some event fired every time form is navigated to but bit later (like <code>OnViewLoaded</code> event) ?</p>
  
  <p>OR</p>
  
  <p>At what point OS stops its timeout timer ? 
  As i see at <code>OnNavigated</code> it is forbidden to show modal dialogs, but at <code>Loaded</code> handler - already possible</p>