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    <p>In Windows Forms, calling <code>Invoke</code> on some control (such as your main form) will indeed throw if that control is disposed (e.g. the user closed the form). A simple way to avoid it would be using the winforms <code>SynchronizationContext</code> class. This works because the <code>WindowsFormsSynchronizationContext</code> keeps an internal control of its own, on which it calls the <code>Invoke</code>/<code>BeginInvoke</code> commands. see <a href="https://stackoverflow.com/questions/4190299/exploiting-the-backgroundworker-for-cross-thread-invocation-of-gui-actions-on-win/4192954">Exploiting the BackGroundWorker for cross-thread invocation of GUI actions on Winforms controls?</a></p> <p>In WPF, the <code>SynchronizationContext</code> delegates to the dispatcher so using either of them is the same. However, since the WPF dispatcher is not disposable as controls are (it can be shut down though), you don't have to worry about an <code>ObjectDisposedException</code>. However, I believe calling <code>Invoke</code> may hang your application if the dispatcher has been shut down (since it would wait for an operation that would never complete) - calling <code>BeginInvoke</code> instead should take care of that. That being said, ThreadPool threads (which are the ones created by the default Task scheduler, as in your case above) are Background threads which would not stop your process from exiting - even if they are hung on a <code>Dispatcher.Invoke</code> call.</p> <p>In short, in both Windows Forms and WPF, using <code>SynchronizationContext.Post</code> (which in WPF is equivalent to <code>Dispatcher.BeginInvoke</code>) will take care of the general problem you're talking about.</p> <p><strong>Let's change the scenario a bit - what happens when the user closes the form while the UI is being updated in the Dispatcher.Invoke routine?</strong> That can't happen - while the <code>Dispatcher.Invoke</code> invoke is running the UI thread is busy, in particular it can't process user input such as the keyboard or mouse click a user would need to close the form.</p>
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    1. POWhat happens when a Task is running and it's window is closed?
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    1. USOhad Schneider
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    1. POWhat happens when a Task is running and it's window is closed?
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    1. CODo I understand correctly, that a call to "this.Dispatcher" inside my Task will never throw an ObjectDisposedException? But what about all the UI objects I'm referencing inside the Invoke routine? Finally as per your statement - "Dispatcher.BeginInvoke) will take care of the general problem you're talking about" - would I not have had my application crash when using the ThreadPool directly (as described in my post) if I had used BeginInvoke instead of Invoke?
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    2. COThere is only one UI thread (the dispatcher thread), so while you're inside the invoke routine the user can't close the form. He can only do so just before the task runs, in which case your invoke routine would never run (since the Dispatcher message loop won't be active). In terms of crashing/hanging, there's no difference between using the threadpool and using tasks since the latter are implemented in terms of the former (so yes, I believe BeginInvoke won't crash with the threadpool as well)
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    3. COIn any case, I recommend you debug and check whether your WPF elements are "shut down" when you think they are: http://social.msdn.microsoft.com/Forums/en/wpf/thread/3bb34dcf-433e-4ddd-8b6e-13b83f075eed
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