function Popup(myurl,mywidth,myheight) {
   var xLeft = (screen.width - mywidth) / 2 ;
   var xTop = (screen.height - myheight) / 2;
   var cLeft = 420;
   var cTop = 410;
   var cwidth = mywidth+20;
   var cheight = myheight+25;
   var cUrl = "images/"+myurl
   var myoptions = "resizable=no,toolbar=no,scrollbars=no,menubar=no,status=no,width="+cwidth+",height="+cheight+",left="+ cLeft +",top="+ cTop +"";
   window.open(cUrl, "displayWindow", myoptions);
   }