var visibleMenu = '';

function showMenu(myMenu, menuPosition) {
  if(visibleMenu != myMenu)
  {
    var dropDownItem = document.getElementById(myMenu);
    dropDownItem.style.display = "block";

    var menuItem = document.getElementById(menuPosition);
    var menuItem = document.getElementById(menuPosition);
    menuItem.style.backgroundImage = "url('/epigenomeatlas/images/topNavigation_background_hover_no_dropdown.png')";

    visibleMenu = myMenu;
  }
}

function hideMenu(hideMenu, menuPosition) {
  var dropDownItem = document.getElementById(hideMenu);
  dropDownItem.style.display = "none";

  var menuItem = document.getElementById(menuPosition);
  changeBackgroundOut(menuItem);
  visibleMenu = '';
}

function changeBackgroundOver(menuItem)
{
  menuItem.style.backgroundImage = "url('/epigenomeatlas/images/topNavigation_background_hover.png')";
}

function changeBackgroundOut(menuItem)
{
  menuItem.style.backgroundImage = "url('/epigenomeatlas/images/topNavigation_background.png')";
}