function ladFenster(datei,breit,hoch)
  {
    var posVonLinks = (screen.availWidth-breit)/2
    var posVonOben = (screen.availHeight-hoch)/2
    var newWindow = window.open(datei,'','left='+posVonLinks+', top='+posVonOben+', width='+breit+', height='+hoch+', fullscreen=no,toolbar=no,status=yes,menubar=no,scrollbars=yes,resizable=yes,location=no')
  }