open pannel

[Eva]

Can we open a pannel from a button click?

[Cat Cheshire]

The PanelBar items have a property called "Expanded" that you can use for expanding them with a server-side code.
At client-side the corresponding property is called set_expanded:

<telerik:RadPanelBar runat="server"  ID="RadPanelBar1" Height="300px">
        <Items>
            <telerik:RadPanelItem  Text="ASP.NET controls">
                <Items>
                    <telerik:RadPanelItem Text="RadMenu" Value="1">
                    </telerik:RadPanelItem>
                    <telerik:RadPanelItem Text="RadTabStrip">
                    </telerik:RadPanelItem>
                    <telerik:RadPanelItem Text="RadPanelBar">
                    </telerik:RadPanelItem>
                    <telerik:RadPanelItem Text="RadTreeView">
                    </telerik:RadPanelItem>
                </Items>
            </telerik:RadPanelItem>
            <telerik:RadPanelItem Text="WinForms controls">
                <Items>
                    <telerik:RadPanelItem Text="RadMenustrip">
                    </telerik:RadPanelItem>
                    <telerik:RadPanelItem Text="RadTabStrip">
                    </telerik:RadPanelItem>
                    <telerik:RadPanelItem Text="RadToolStrip">
                    </telerik:RadPanelItem>
                </Items>
            </telerik:RadPanelItem>
            <telerik:RadPanelItem Text="Other projects">
                <Items>
                    <telerik:RadPanelItem Text="SiteFinity">
                    </telerik:RadPanelItem>
                    <telerik:RadPanelItem Text="Reporting">
                    </telerik:RadPanelItem>
                    <telerik:RadPanelItem Text="RadAjax">
                    </telerik:RadPanelItem>
                </Items>
            </telerik:RadPanelItem>
        </Items>
    </telerik:RadPanelBar>
<script type="text/javascript">
    function ExpandFirst() {
        var panelBar = $find("<%=RadPanelBar1.ClientID %>");
        panelBar.get_items().getItem(0).set_expanded(true);

    }
</script>
<input type="button" value="expand first item" onclick="ExpandFirst();" />
<asp:Button ID="btnExpand" runat="server" Text="expand last item"
    OnClick="btnExpand_OnClick" />

protected void btnExpand_OnClick(object sender, EventArgs e)
{
    this.RadPanelBar1.Items[2].Expanded = true;
}