function popup(url,w,h) {
   var maxwidth = screen.width;
   var maxheight = screen.height-150;
   var param = 'dependent=no,resizable=no,location=no,directories=no,status=yes,menubar=no,scrollbars=auto,toolbar=no,width='+w+',height='+h;
   inhaltFenster = window.open(url,'',param);
   inhaltFenster.blur();
   inhaltFenster.moveTo((maxwidth-w)/2,(maxheight-h)/2);
   inhaltFenster.focus();
 }