if (window.addEventListener) {
  window.addEventListener ("load", rememberMouseEvent, false);
}
else if (window.attachEvent) {
  window.attachEvent ("onload", rememberMouseEvent);
}

function rememberMouseEvent () {
  document.getElementById("content").onmousemove = function (event) {
    mouseEvent = (event) ? event : ((window.event) ? window.event : "");
  }
}

function open_popup(anchorNode) {
  var text1 = anchorNode.firstChild.data;
  var text2 = glossar_entries[text1];
  document.getElementById('notion').innerHTML = '<strong>'+ text1 +':</strong>';
  document.getElementById('explanation').innerHTML = text2;
  var tooltip = new Tooltip(anchorNode, 'glossar_tooltip');
  tooltip.showTooltip(mouseEvent);
}