function hoverDot(number) {
  if (number < 0) return;
  if (number > 6) return;
  var strMenuName = 'dot_' + number + '_menu';
  var strDivName = 'dot_' + number;
  
  setHoverAttribute(getSaveHTMLElementByID(strMenuName));
  setHoverAttribute(getSaveHTMLElementByID(strDivName));
}

function unhoverDot(number) {
  if (number < 0) return;
  if (number > 6) return;
  var strMenuName = 'dot_' + number + '_menu';
  var strDivName = 'dot_' + number;
  
  removeHoverAttribute(getSaveHTMLElementByID(strMenuName));
  removeHoverAttribute(getSaveHTMLElementByID(strDivName));
}

function getSaveHTMLElementByID(strID) {
  if (document.getElementById) return document.getElementById(strID);
  if (document.layers) return document[strID]; // NS 4.x
  if (document.all) return document.all[strID]; // IE 3.x and up
  return null;
}

function setHoverAttribute(element) {
  if (element == null) return;
  if (((element.getAttribute('class') == null) || (element.getAttribute('class') == '')) && (element.className == '')) {
    element.setAttribute('class', 'hover');
    element.className = 'hover';
    return;
  } else {
    var strClass = element.getAttribute('class');
    if (strClass == null || strClass == '') strClass = element.className;
    strClass = strClass.replace(/hover/g, '');
    strClass += ' hover';
    strClass = strClass.replace(/^\s*(.*?)\s*$/, '$1'); // trim
    strClass = strClass.replace(/\s+/g, ' '); // simplify
    element.setAttribute('class', strClass); 
    element.className = strClass;
    return;
  }
}

function removeHoverAttribute(element) {
  if (element == null) return;
  if (((element.getAttribute('class') == null) || (element.getAttribute('class') == '')) && (element.className == '')) return;
  strClass = element.getAttribute('class');
  if (strClass == null || strClass == '') strClass = element.className;
  strClass = strClass.replace(/hover/g, '');
  strClass = strClass.replace(/^\s*(.*?)\s*$/, '$1'); // trim
  strClass = strClass.replace(/\s+/g, ' '); // simplify
  if (strClass == null || strClass == '')  {
    element.removeAttribute('class');
    element.className = '';
    return;
  } else {
    element.setAttribute('class', strClass);
    element.className = strClass;
    return;
  }
}


function showLayer(layer) {
  setHoverAttribute(getSaveHTMLElementByID(layer));
	setHoverAttribute(getSaveHTMLElementByID(layer + '_text'));
}


function hideLayer(layer) {
	removeHoverAttribute(getSaveHTMLElementByID(layer));
	removeHoverAttribute(getSaveHTMLElementByID(layer + '_text'));
}