title: What happens when I try to remove handler that was never added?
body: <p>I have an event handler.
  I add an event 5 secs after start to it like this:</p>
  
  <pre><code>AddHandler MyHandler, AddressOf DoStuff
  </code></pre>
  
  <p>Now when disposing the whole form, I need to</p>
  
  <pre><code>Private Sub Unsubscribe()
       RemoveHandler MyHandler, AddressOf DoStuff
  End Sub
  </code></pre>
  
  <p>What if I close the form earlier than 5 secs after start? Is it a problem when I try to <code>RemoveHandler</code> that was never added? Is it the same in c# with <code>+=</code> and <code>-=</code>?</p>