if (document.images) {
  menu_therapies_on = new Image();
  menu_therapies_off = new Image();
  menu_therapies_on.src = "/img/tabmenu/therapies_hover.gif";
  menu_therapies_off.src = "/img/tabmenu/therapies_off.gif";

  menu_retreats_on = new Image();
  menu_retreats_off = new Image();
  menu_retreats_on.src = "/img/tabmenu/retreats_hover.gif";
  menu_retreats_off.src = "/img/tabmenu/retreats_off.gif";

  menu_detox_on = new Image();
  menu_detox_off = new Image();
  menu_detox_on.src = "/img/tabmenu/detox_hover.gif";
  menu_detox_off.src = "/img/tabmenu/detox_off.gif";

  menu_events_on = new Image();
  menu_events_off = new Image();
  menu_events_on.src = "/img/tabmenu/events_hover.gif";
  menu_events_off.src = "/img/tabmenu/events_off.gif";

  menu_resources_on = new Image();
  menu_resources_off = new Image();
  menu_resources_on.src = "/img/tabmenu/resources_hover.gif";
  menu_resources_off.src = "/img/tabmenu/resources_off.gif";
  
  menu_aboutus_on = new Image();
  menu_aboutus_off = new Image();
  menu_aboutus_on.src = "/img/tabmenu/about_hover.gif";
  menu_aboutus_off.src = "/img/tabmenu/about_off.gif";

  menu_centre_on = new Image();
  menu_centre_off = new Image();
  menu_centre_on.src = "/img/tabmenu/centre_hover.gif";
  menu_centre_off.src = "/img/tabmenu/centre_off.gif";

  menu_shop_on = new Image();
  menu_shop_off = new Image();
  menu_shop_on.src = "/img/tabmenu/shop_hover.gif";
  menu_shop_off.src = "/img/tabmenu/shop_off.gif";

}

function imgOn(imgName) {
  if (document.images) {
    document[imgName].src = eval(imgName + "_on.src");
  }
}

function imgOff(imgName) {
  if (document.images) {
    document[imgName].src = eval(imgName + "_off.src");
  }
}