var divElem = 'AlertDiv';
var messageElem = 'AlertMessage';
var bodyTag = 'bodytag';
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);

function ToggleAlertDiv(visString){
    /*if (visString == 'hidden')
        $get(bodyTag).style.backgroundColor = 'white';                         
    else
        $get(bodyTag).style.backgroundColor = 'gray';                         
    */
    var adiv = $get(divElem);
    adiv.style.visibility = visString;
}

function ClearErrorState() {
    $get(messageElem).innerHTML = '';
    ToggleAlertDiv('hidden');                     
}

function EndRequestHandler(sender, args){
    if (args.get_error() != undefined){
        var errorMessage;
        if (args.get_response().get_statusCode() == '200'){
            errorMessage = args.get_error().message.replace(/Sys.WebForms.PageRequestManagerServerErrorException: /, "");
        }
        else{
            // Error occurred somewhere other than the server page.
            errorMessage = 'An unspecified error occurred. ';
        }
        args.set_errorHandled(true);
        ToggleAlertDiv('visible');
        $get(messageElem).innerHTML = errorMessage;
    }
}