ล๊อก ScrollBar ทั้งหมดที่ไม่ใช่ jQuqery ที่ PopUp ทำอย่างไร

<script>
var basepath = "";

					$(function() {
							$( "#longdialog" ).dialog({
								autoOpen: false,
								show: "blind",
								hide: "blind",
								width: "550px",
								modal:true
							});
					
					$("#opener").click(function() {
						$( "#longdialog" ).dialog( "open" );
						return false;
					});
				});	
	
function check(pid)
{
		var strURL= basepath + "post.php";	
		var prms = 'pid=' + pid ; 
	
	         $.ajax({
             type: "POST",
             url: strURL,
             data: prms,
             success: function(result){ 
			 		document.body.style.overflow = 'hidden';
				  $("#longdialog").html(result);
			 }
         });  
}	
</script>
  <div id="longdialog" title="ทดสอบ Dialog">
  </div>