RadWindow is based on an IFRAME and by default it displays a content page set with the NavigateUrl property. Note that in this case, these are two completely different documents and you cannot access the server-side logic in one of the pages from the other one.
In such scenario, you should use the client-side API
of the control. A sample implementation of such logic is available in this demo
. In it, after RadWindow is closed, we use RadAjaxManager's API to invoke an Ajax call that would fire server-side code.
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