Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(empezarRequest);
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(terminarRequest);    
            
function empezarRequest(sender, args){	     
	OverlayProgressPanel(PanelUpdate,PanelProgreso);   
}

function terminarRequest(sender, args) {
	$get(PanelProgreso).style.display = "none";        
} 

function findBothPos(obj){
    var curleft = curtop = 0;
    if (obj.offsetParent){
        curleft = obj.offsetLeft;
        curtop = obj.offsetTop;
        while (obj = obj.offsetParent){
            curleft += obj.offsetLeft;
            curtop += obj.offsetTop;
        }
    }
    return [curleft,curtop];
}

function OverlayProgressPanel(UpdatePanel,ProgresoPanel){
    var update = $get(UpdatePanel);
    var progress = $get(ProgresoPanel);
    var pos = findBothPos(update);    
    progress.style.cssText = 'position: absolute;background-color: #FFF; z-index: 99999; opacity: 0.9; -moz-opacity: 0.9; filter: alpha(opacity=50); left: ' + pos[0] + 'px; top: ' + pos[1] + 'px; width: ' + update.offsetWidth + 'px; height: ' + update.offsetHeight + 'px';    

}