title: what is the correct way to cancel multiple tasks in c#
body: <p>I have a button thats spawns 4 tasks. The same button changes to a cancel button and clicking this should cancel all 4 tasks. Should I pass the same cancel token to all 4 tasks and have them poll on the same token for IsCancelRequested ? I am confused after reading the msdn doc on <a href="http://msdn.microsoft.com/en-us/library/dd642265.aspx">createlinkedtokensource</a>. How is this normally done ? thank you</p>
  
  <p>Update: Task.WaitAll() waits tills <strong>all tasks complete execution</strong>. Similarly how to know when <strong>all tasks have been canceled</strong> once the shared cancel token source is set to cancel.</p>