Although you may overload a Mediator's responsibilities by having it deal additionally with the Popups that its view component invokes, you will find this is really not a good way to go. For apps with popups that are more complex, you generally want a mediator just for the popup. But that means registering and unregistering that popup's Mediator when invoked and is dismissed.
Here is a great solution:
http://www.nutrixinteractive.com/blog/?p=76In this article, Simon creates a simple 'PopManager' class with static functions for showing a popup and registering its Mediator, or dismissing it and removing the Mediator.
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