Cannot Collapse Root Items
PROBLEM
Root items that have ItemTemplate defined cannot be collapsed. This is by design and can be observed on our online demo.
SOLUTION
Add an additional item with no text as a child item of the root item and set its ItemTemplate.
EXAMPLE
The root item of this panelbar cannot be collapsed:
<telerik:RadPanelBar RenderMode="Lightweight" ID="RadPanelBar2" runat="server" ExpandMode="FullExpandedItem">
<Items>
<telerik:RadPanelItem runat="server" Text="Root RadPanelItem1">
<ItemTemplate>
<telerik:RadComboBox RenderMode="Lightweight" ID="RadComboBox1" runat="server">
</telerik:RadComboBox>
</ItemTemplate>
</telerik:RadPanelItem>
</Items>
</telerik:RadPanelBar>
The root item of this panelbar can be collapsed:
<telerik:RadPanelBar RenderMode="Lightweight" ID="RadPanelBar1" runat="server">
<Items>
<telerik:RadPanelItem runat="server" Text="Root RadPanelItem1">
<Items>
<telerik:RadPanelItem>
<ItemTemplate>
<telerik:RadComboBox RenderMode="Lightweight" ID="RadComboBox1" runat="server">
</telerik:RadComboBox>
</ItemTemplate>
</telerik:RadPanelItem>
</Items>
</telerik:RadPanelItem>
</Items>
</telerik:RadPanelBar>