Hi Roland,
I am not sure how you reproduce the problem. Here is a demo, which works. Feel free to modify it and send it back for further inspection.
<%@ Page Language="C#" %>
<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<
head
runat
=
"server"
>
<
meta
http-equiv
=
"content-type"
content
=
"text/html;charset=utf-8"
/>
<
title
>RadControls</
title
>
<
style
type
=
"text/css"
>
html,body,form
{
height:100%;
margin:0;
padding:0;
}
</
style
>
</
head
>
<
body
>
<
form
id
=
"form1"
runat
=
"server"
>
<
asp:ScriptManager
ID
=
"ScriptManager1"
runat
=
"server"
/>
<
telerik:RadFormDecorator
ID
=
"RadFormDecorator1"
runat
=
"server"
DecoratedControls
=
"Buttons"
/>
<
telerik:RadAjaxManager
ID
=
"RadAjaxManager1"
runat
=
"server"
>
<
AjaxSettings
>
<
telerik:AjaxSetting
AjaxControlID
=
"btnDoStuff"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"pnlMainNav"
UpdatePanelHeight
=
"100%"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
</
AjaxSettings
>
</
telerik:RadAjaxManager
>
<
asp:Button
ID
=
"btnDoStuff"
runat
=
"server"
Text
=
"do stuff"
/>
<
telerik:RadPanelBar
ID
=
"pnlMainNav"
runat
=
"server"
Width
=
"100%"
Height
=
"100%"
ExpandMode
=
"FullExpandedItem"
>
<
Items
>
<
telerik:RadPanelItem
Text
=
"Item 1"
Expanded
=
"true"
>
<
Items
>
<
telerik:RadPanelItem
Text
=
"sub item 1"
/>
<
telerik:RadPanelItem
Text
=
"sub item 2"
/>
<
telerik:RadPanelItem
Text
=
"sub item 3"
/>
</
Items
>
</
telerik:RadPanelItem
>
<
telerik:RadPanelItem
Text
=
"Item 2"
>
<
Items
>
<
telerik:RadPanelItem
Text
=
"sub item 1"
/>
<
telerik:RadPanelItem
Text
=
"sub item 2"
/>
<
telerik:RadPanelItem
Text
=
"sub item 3"
/>
</
Items
>
</
telerik:RadPanelItem
>
<
telerik:RadPanelItem
Text
=
"Item 3"
>
<
Items
>
<
telerik:RadPanelItem
Text
=
"sub item 1"
/>
<
telerik:RadPanelItem
Text
=
"sub item 2"
/>
<
telerik:RadPanelItem
Text
=
"sub item 3"
/>
</
Items
>
</
telerik:RadPanelItem
>
<
telerik:RadPanelItem
Text
=
"Item 4"
>
<
Items
>
<
telerik:RadPanelItem
Text
=
"sub item 1"
/>
<
telerik:RadPanelItem
Text
=
"sub item 2"
/>
<
telerik:RadPanelItem
Text
=
"sub item 3"
/>
</
Items
>
</
telerik:RadPanelItem
>
</
Items
>
</
telerik:RadPanelBar
>
</
form
>
</
body
>
</
html
>
Regards,
Dimo
the Telerik team
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