// hover/unhover menu
function HoverMenu(idMenu, bHover)
{
  var elem = document.getElementById(idMenu);
  if (elem != null)
  {
    var classNameMenu     = "menu";
    if (bHover)
    {
      classNameMenu += "_hover";
    }
    elem.className = classNameMenu;
  }
  else
  {
    alert("Unable to find element ID: " + idMenu);
  }
}