function showPopup( hoverItem, popupText ) {
  var OFFSET_TOP = 25;
  var OFFSET_LEFT = -250;
  var hoverTop = hoverItem.offsetTop;
  var hoverLeft = hoverItem.offsetLeft;
  popupText.style.top = hoverTop + OFFSET_TOP + 'px';
  popupText.style.left = hoverLeft + OFFSET_LEFT + 'px';
  popupText.style.visibility = "visible";
}
function hidePopup( popupText ) {
  // document.getElementById( popupText ).style.visibility = "hidden";
  popupText.style.visibility = "hidden";
}