title: What causes the UnhandledExceptionEventArgs.IsTerminating flag to be true or false?
body: <p>When subscribed to events on <code>AppDomain.CurrentDomain.UnhandledException</code> what criteria causes the <code>UnhandledExceptionEventArgs</code> <code>IsTerminating</code> flag to be true?  I.e. what causes an exception to be considered fatal?</p>
  
  <p>Is it the case that by default all unhandled exceptions will be fatal unless configured otherwise?</p>