function wopen(url, name, w, h)
{
     
      wleft = (screen.width - w) / 2;
      wtop = (screen.height - h) / 2;
      if (wleft < 0) {
       
        wleft = 0;
      }
      if (wtop < 0) {
        wtop = 0;
      }
      
        
      var win = window.open(url,'CurrencyConverter',
        'width=' + w + ', height=' + h + ', ' +
        'left=' + wleft + ', top=' + wtop + ', ' +
        'location=no, menubar=no, ' +
        'status=no, toolbar=no, scrollbars=yes, resizable=no');
      
      win.resizeTo(w, h);
      
      win.moveTo(wleft, wtop);
      win.focus();
      return win;
    }