General
    You can embed any content inside RadPanelBar's ContentTemplate and HeaderTemplate:
    
        - HTML markup
- ASP.NET server controls
- Third-party controls (other Telerik controls as well)
        
        <telerik:RadPanelItem Expanded="true">
            <HeaderTemplate>
                <telerik:RadMenu ID="RadMenu1" runat="server">
                    ...
                </telerik:RadMenu>
            </HeaderTemplate>
            <ContentTemplate>
                <telerik:RadMultiPage runat="server" ID="RadMultiPage1">
                    ...
                </telerik:RadMultiPage>
            </ContentTemplate>
        </telerik:RadPanelItem>
     
    
        All server controls located in the templates are directly accessible by their IDs
        on Page-level. Instead of using the common syntax
        
        RadPanelBar1.Items[0].Header.FindControl("RadMenu1") //inside a HeaderTemplate
        RadPanelBar1.Items[0].FindControl("RadMultiPage1") //inside a ContentTemplate
    
        you can use 
RadMenu1 or 
RadMultiPage1 to reference the control located
        inside the respective template of the first root Item of a PanelBar.
    
        HeaderTemplate
    
        The content in the HeaderTemplate replaces the default content of the PanelItem
        header. Clicking anywhere on the header will still collapse/expand the Item unless
        the click event bubbling is manually stopped.
    
    If you want to stop the propagation of the click event you can wrap the target content
    with a 
<div> element and handle its click event in this way:
    
        
        function stopPropagation(e) {
            e.cancelBubble = true;
            if (e.stopPropagation)
                e.stopPropagation();
        }
    
     
    
        Note: In this demo we manually expand/collapse
        the Item when clicking on the RadMenu because it already does the mentioned above.
    
    
        ContentTemplate
    
        The purpose of the ContentTemplate is to provide an Item with an animated expandable/collapsible
        container, which holds rich HTML content instead of a standard child Item structure,
        e.g. The ContentTemplate is defined per Item and is available on every level. An
        Item can have either a ContentTemplate or child Items.