function openWindow( url, name,w,h,scroll)
{
     var ah = window.screen.availHeight;
     var aw = window.screen.availWidth;
     var l = (aw - w) / 2;
     var t = (ah - h) / 2;

     params = "";
     params += "left="+l+",top="+t+",screenX="+l+",screenY="+t+",height="+h+",width="+w+",resizable=no,status=no,scrollbars="+(scroll?'Yes':'No');

     var win_popup = window.open( url, name, params );
}