function swap_image( img_tag_id, path, mode ){
  if ( img_tag_id != undefined && path != "" && path != undefined ){
    var id = "menu_item_" + img_tag_id;
    if ( document.getElementById( id ) != undefined ){
      var image = document.getElementById( id );
      if ( menu_hover_images[img_tag_id] != undefined ){
        if ( mode == "normal" ){
          image.src = menu_hover_images[img_tag_id]['image_normal'].src;
        }
        if ( mode == "hover"){
          image.src = menu_hover_images[img_tag_id]['image_hover'].src;
        }
      }
    }
  }
}