or

<telerik:RadWindowManager ID="RadWindowManager_Default" runat="server" Skin="Default" Animation="Fade" AnimationDuration="300" DestroyOnClose="True"> </telerik:RadWindowManager> ... code behind ... public RadWindowManager RWM_Default { get { return RadWindowManager_Default; } set { RadWindowManager_Default = value; } }RadWindow Window_FR_View; protected void Page_Load(object sender, EventArgs e) { //Add window for popup Window_FR_View = new RadWindow(); Window_FR_View.ID = "RadWindow_FR"; Window_FR_View.NavigateUrl = "OnTime_Reports/fire_report_view_popup.aspx"; Window_FR_View.Height = Unit.Pixel(600); Window_FR_View.Width = Unit.Pixel(400); Window_FR_View.Modal = true; Window_FR_View.VisibleStatusbar = false; Window_FR_View.Behaviors = Telerik.Web.UI.WindowBehaviors.Close; ((_Default)Page).RWM_Default.Windows.Add(Window_FR_View); //Register Javascript for RadWindow String script4 = "" + "function openRadWindow_FR(Page_To_Open, RadWindow_Control_ID) " + "{" + "radopen(Page_To_Open, RadWindow_Control_ID);" + "}"; ScriptManager.RegisterStartupScript(Page, Page.GetType(), "FR_LOAD", script4, true);protected void Button_Run_Fire_Report_OnClick(object sender, EventArgs e) { String script5 = "openRadWindow_FR(\"OnTime_Reports/fire_report_view_popup.aspx\", \"" + Window_FR_View.ClientID + "\");"; ScriptManager.RegisterStartupScript(Page, Page.GetType(), "FR_LOAD_LIST", script5, true); }