RadWindow for ASP.NET AJAX

private void Page_Load(object sender, System.EventArgs e)
{
    //Set properties present only in RadWindowManager
    //Set skin
    WindowManager.Skin = "Monochrome";
    //Set the same height to all windows
    WindowManager.Height = Unit.Pixel(250);
    int offsetLeft = 0;
    //Loop through all windows in the WindowManager.Windows collection
    foreach (Telerik.Web.UI.RadWindow win in WindowManager.Windows)
    {
        //Set whether the first window will be visible on page load
        win.VisibleOnPageLoad = true;
        //Set the behavior (whether the window will allow to be minimized, maximized and/or pinned)
        win.Behaviors = Telerik.Web.UI.WindowBehaviors.Maximize | Telerik.Web.UI.WindowBehaviors.Close;

        //Set OffsetElementId - the id (ClientID if a runat=server is used) of a html element, which, when clicked, will automatically open/show the Telerik RadWindow
        win.OffsetElementID = "OffsetElement";
        //Top and Left can be used in conjunction with the OffsetElementId (if no OffsetElementId is specified, the top left corner of the browser window is used
        win.Top = 15;
        win.Left = offsetLeft;
        offsetLeft += 100;
    }

    //Create a new window add it dynamically
    //The window will inherit the default settings of parent WindowManager
    Telerik.Web.UI.RadWindow newWindow = new Telerik.Web.UI.RadWindow();
    newWindow.NavigateUrl = "http://www.sitefinity.com";
    //Set OpenerElementId - the id (ClientID if a runat=server is used) of a html element, which, when clicked, will automatically open/show the Telerik RadWindow
    newWindow.OpenerElementID = OpenerButton.ClientID;
    //Set OffsetElementID - the id (ClientID if a runat=server is used) of a html element, whose left and top position will be used as 0,0 of the Telerik RadWindow object when it is first shown
    newWindow.OffsetElementID = OpenerButton.ClientID;
    //Top and Left can be used in conjunction with the OffsetElementId (if no OffsetElementId is specified, the top left corner of the browser window is used
    newWindow.Top = Unit.Pixel(22);
    newWindow.Left = Unit.Pixel(0);
    //OPTION 1
    //Add the newly created RadWindow to the RadWindowManager's collection
    //WindowManager.Windows.Add(newWindow);
    //OPTION 2
    //since in the for ASP.NET AJAX version you can have a RadWindow outside of a RadWindowManager
    //as a separate control, you can add the newly created RadWindow directly to the form's Controls collection
    form1.Controls.Add(newWindow);

    //Get a reference to the first window in the list
    Telerik.Web.UI.RadWindow firstWindow = WindowManager.Windows[0];
    //Set its navigate URl to be different
    firstWindow.NavigateUrl = "http://www.telerik.com/products/sharepoint/overview.aspx";
}