If I understand you correctly, you want to achieve the following:
1. Open a browser page with a button on it.
2. When you click that button, you want to open a RadWindow and close the browser's page.
If this is so, such functionality is not possible - RadWindow exists only in the context of the page in which it is created. It cannot be used as a standalone popup (i.e. as a replacement of the main browser window).
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