function fenster(URL,WD,HT)
         {  
         var infowin = window.open(URL,'_blank','toolbar=no,resizable=no,scrollbars=no,menubar=no,status=no,width='+WD+',height='+HT);
         infowin.focus();
         infowin.moveTo((screen.width-WD)/2,(screen.height-HT)/2);
         }