function popupwnd(url, targ, width, height, centerwnd){
 var param = 'width='+width + ',height='+height + ',toolbar=no,location=no,scrollbars=yes,menubar=no,status=no,resizable=yes';
 if (centerwnd && !(navigator.userAgent.indexOf('Opera')>=0)){
     param += ",left=" + ((screen.width - width)/2) + ",top=" + ((screen.height-height)/2);
 } else {
     if (centerwnd){         
         param += ",left=" + ((screen.width - width)/2) + ",top=" + (absolute(window.innerHeight-height)/2);
     }
 } 
 var popupWin = window.open(url, targ, param);
 popupWin.focus();
}