Here's an example Pane is not closing on PostBack. I would suggest to use latest DLL of AJAX Control Toolkit
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<style type="text/css">
.accordionHeader
{
border: 1px solid rgb(47, 79, 79);
color: white;
background-color: rgb(46, 77, 123);
font-family: Arial,Sans-Serif;
font-size: 12px;
font-weight: bold;
padding: 5px;
margin-top: 5px;
cursor: pointer;
}
.accordionContent
{
background-color: rgb(211, 222, 239);
border-right: 1px dashed rgb(47, 79, 79);
border-width: medium 1px 1px;
border-style: none dashed dashed;
border-color: -moz-use-text-color rgb(47, 79, 79) rgb(47, 79, 79);
-moz-border-top-colors: none;
-moz-border-right-colors: none;
-moz-border-bottom-colors: none;
-moz-border-left-colors: none;
border-image: none;
padding: 10px 5px 5px;
}
.accordionHeaderSelected
{
border: 1px solid rgb(47, 79, 79);
color: white;
background-color: rgb(80, 120, 179);
font-family: Arial,Sans-Serif;
font-size: 12px;
font-weight: bold;
padding: 5px;
margin-top: 5px;
cursor: pointer;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<cc1:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
</cc1:ToolkitScriptManager>
<cc1:Accordion ID="Accordion1" runat="server" SelectedIndex="0" FadeTransitions="true"
SuppressHeaderPostbacks="true" TransitionDuration="250" FramesPerSecond="40"
HeaderCssClass="accordionHeader" HeaderSelectedCssClass="accordionHeaderSelected"
ContentCssClass="accordionContent" RequireOpenedPane="false" AutoSize="None">
<Panes>
<cc1:AccordionPane ID="AccordionPane1" runat="server">
<Header>
Pane 1
</Header>
<Content>
<asp:Panel ID="Panel1" runat="server">
<cc1:Accordion ID="Accordion2" runat="server" SelectedIndex="0" FadeTransitions="true"
SuppressHeaderPostbacks="true" TransitionDuration="250" FramesPerSecond="40"
HeaderCssClass="accordionHeader" HeaderSelectedCssClass="accordionHeaderSelected"
ContentCssClass="accordionContent" RequireOpenedPane="true" AutoSize="None" Width="220px">
<Panes>
<cc1:AccordionPane ID="AccordionPane3" runat="server">
<Header>
Pane 1
</Header>
<Content>
<asp:Panel ID="Panel3" runat="server">
<asp:LinkButton ID="LinkButton5" Text="Pane1" runat="server" />
</asp:Panel>
</Content>
</cc1:AccordionPane>
<cc1:AccordionPane ID="AccordionPane4" runat="server">
<Header>
Pane 2
</Header>
<Content>
<asp:Panel ID="Panel4" runat="server">
<asp:LinkButton ID="LinkButton1" Text="Pane2" runat="server" />
</asp:Panel>
</Content>
</cc1:AccordionPane>
</Panes>
</cc1:Accordion>
</asp:Panel>
</Content>
</cc1:AccordionPane>
<cc1:AccordionPane ID="AccordionPane2" runat="server">
<Header>
Pane 2
</Header>
<Content>
<asp:Panel ID="Panel2" runat="server">
<cc1:Accordion ID="Accordion3" runat="server" SelectedIndex="0" FadeTransitions="true"
SuppressHeaderPostbacks="true" TransitionDuration="250" FramesPerSecond="40"
HeaderCssClass="accordionHeader" HeaderSelectedCssClass="accordionHeaderSelected"
ContentCssClass="accordionContent" RequireOpenedPane="true" AutoSize="None" Width="220px">
<Panes>
<cc1:AccordionPane ID="AccordionPane5" runat="server">
<Header>
Pane 1
</Header>
<Content>
<asp:Panel ID="Panel5" runat="server">
<asp:LinkButton ID="LinkButton2" Text="Pane1" runat="server" />
</asp:Panel>
</Content>
</cc1:AccordionPane>
<cc1:AccordionPane ID="AccordionPane6" runat="server">
<Header>
Pane 2
</Header>
<Content>
<asp:Panel ID="Panel6" runat="server">
<asp:LinkButton ID="LinkButton3" Text="Pane2" runat="server" />
</asp:Panel>
</Content>
</cc1:AccordionPane>
</Panes>
</cc1:Accordion>
</asp:Panel>
</Content>
</cc1:AccordionPane>
</Panes>
</cc1:Accordion>
</form>
</body>
</html>
