The following article shows how confirmation can be shown before closing a RadWindow: http://www.telerik.com/help/aspnet-ajax/window-application-confirm-closing.html
if you want to let the user control this.
Otherwise - just remove the calls to GetRadWindow().close(); from the dialog page in this demo: http://demos.telerik.com/aspnet-ajax/controls/examples/integration/gridandwindow/defaultcs.aspx?product=window
You can download the demos from your account and examine and/or modify their code freely. The refreshGrid() function triggers the grid refresh while the close() method of the RadWindow is what closes the popup. If you do not want to close it in all cases just call it when you want to.
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