title: CancellationToken - Register Handler after Cancel Requested
body: <p>In the absence of constructing a quick test bed; I thought I would quickly ask SO to see if anyone knows that answer off hand.</p>
  
  <p>Plus it might have the added benefit of informing other users who may encounter similar situations..</p>
  
  <p>Let's say I have a long lived CancellationTokenSource with many many different components registering handlers on the CancellationToken.</p>
  
  <p>If cancel is requested and the registered callbacks are all invoked and then following that point another handler is registered; does the cancel callback still fire for that new call back at the point of registration?</p>
  
  <p>Cheers in advance!</p>