function aktivieren(navid) {
  var ZielDatei = "index.php?navid=" + navid + "&pos=" + getScrollY();
  var gehezu    = "top.loca" + "tion.hr";

  eval(gehezu + 'ef=ZielDatei');
}

function getScrollY() {
  var scrOfY = 0;
  if( typeof( window.pageYOffset ) == 'number' ) {
    //Netscape compliant
    scrOfY = window.pageYOffset;
  } else if( document.body && document.body.scrollTop ) {
    //DOM compliant
    scrOfY = document.body.scrollTop;
  } else if( document.documentElement && document.documentElement.scrollTop ) {
    //IE6 standards compliant mode
    scrOfY = document.documentElement.scrollTop;
  }
  return scrOfY;
}