I checked my html page generated by asp.net and I can see this line
Sys.Application.initialize();
Sys.Application.add_init(function() {
$create(AjaxControlToolkit.CollapsiblePanelBehavior,
{
"ClientStateFieldID":"rptActiveQuotes_ctl01_qcQuote_cpeDetails_ClientState",
"CollapseControlID":"rptActiveQuotes_ctl01_qcQuote_imgShowHide",
"Collapsed":true,
"CollapsedImage":"Images/expandablePlus.gif",
"ExpandControlID":"rptActiveQuotes_ctl01_qcQuote_imgShowHide",
"ExpandedImage":"Images/expandableMinus.gif",
"ImageControlID":"rptActiveQuotes_ctl01_qcQuote_imgShowHide",
"id":"rptActiveQuotes_ctl01_qcQuote_cpeDetails"
},
null,
null,
$get("rptActiveQuotes_ctl01_qcQuote_pDetails"));
});
I think it's generated from CollapsiblePanelExtender with name cpeDetails. And I see you can pass number of events to it, wich is now null (third argument). What should I do to set add_ended event there?