var setcard_fenster;
function OpenPopup(url,w,h) {

   var left = (screen.width - w)/2;
   var top  = (screen.height - h)/2;
   var params = 'width='+w+',height='+h+',left='+left+',top='+top+'toolbars=no,scrollbars=no,menubar=no,location=no';
   if(setcard_fenster) setcard_fenster.close();
   setcard_fenster = window.open(url,'window',params);
}