In 3.x you can subscribe for
OnSaving() method of the ControlDesigner that is called by ControlEditor when you are about to save the data. For the "cancel" button, there is no server side event. The RadWindow is closed with client script.
In Sitefinity 4.x
You can subscribe for the click event of the save button when you initialize the client component
To get a reference to the cancel button you need to subscribe for
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