The easiest way to get the textbox values in the code behind is by finding the respective textbox controls. Firstly you should get a reference to the dock's user control, and for this task you need to set ID to it. After we have a reference to the user control, we can use its FindControl method to get a reference to any control in the UserControl.
I have modified the MyPortal demo to show this behavior. It is attached to the thread. When running it add the ExchangeRates Widget and then press the "Save" button.
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