var popUpWin=0;
var width = 750;
var height = 550;
var left=(screen.width-width)/2;
var top=(screen.height-height)/2;
var URLStr="http://gribha-guestbook.ap3comparis.com/index.php?lang=fr";
    
function popUpWindow(){
      if(popUpWin){
        if(!popUpWin.closed) popUpWin.close();
      }
      popUpWin = open(URLStr, 'popUpWin', 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=no,copyhistory=yes,width='+width+',height='+height+',left='+left+', top='+top+',screenX='+left+',screenY='+top+'');
    }