title: Communication between a custom view embedded in a view
body: <p>I have created some extended UI controls based on the default android widgets (Button, ProgressBar). At some point, in the custom control, I want to communicate with the view that contains the custom control. For example, I want to pass the current value of the ProgressBar or a value from the Button.
  What is the best approach? Is it possible to create a custom event (like the "onClick") and then have in the container class an handler? Or there is some better approach?
  Thank you in advance! ;)</p>