//Asp.net Ajax UpdatePanel Simultaneous Updates Handler

var PageRequestManagerEx =
{
_initialized : false,

init : function()
{
if (!PageRequestManagerEx._initialized)
{
var _prm = Sys.WebForms.PageRequestManager.getInstance();
var _callQueue = new Array();
var _executingElement = null;

_prm = Sys.WebForms.PageRequestManager.getInstance();

_prm.add_initializeRequest(initializeRequest);
_prm.add_endRequest(endRequest);

PageRequestManagerEx._initialized = true;
}

function initializeRequest(sender, args)
{
if (_prm.get_isInAsyncPostBack())
{
//if we are here that means there already a call pending.

//Get the element which cause the postback
var postBackElement = args.get_postBackElement();

//We need to check this otherwise it will abort the request which we made from the
//end request
if (_executingElement != postBackElement)
{
// Grab the event argument value
var evArg = $get("__EVENTARGUMENT").value;
//alert(evArg);

//Does not match which means it is another control
//which request the update, so cancel it temporary and 
//add it in the call queue
args.set_cancel(true);
Array.enqueue(_callQueue, new Array(postBackElement, evArg));
}

//Reset it as we are done with our matching
_executingElement = null;
}
} 

function endRequest(sender, args)
{
//Check if we have a pending call
if (_callQueue.length > 0)
{
//Get the first item from the call queue and setting it
//as current executing item
_executingElement = Array.dequeue(_callQueue);



var _element = _executingElement[0];
var _eventArg = _executingElement[1];

//Now Post the from which will also fire the initializeRequest
_prm._doPostBack(_element.id, _eventArg);
}
} 

}
}

if (typeof(Sys) != 'undefined')
{
Sys.Application.notifyScriptLoaded();
}