function MenuOn(x){ 
   document.getElementById("submenu"+x).style.visibility="visible";
   document.getElementById("st"+x).src="/images/gnabi_nav"+x+"on.jpg";
}
function MenuOff(x){ 
   document.getElementById("submenu"+x).style.visibility="hidden"; 
   document.getElementById("st"+x).src="/images/gnabi_nav"+x+".jpg";
}
function preload() {
  if (document.images) {
    var imagePreloads = new Array();
    for (var i = 1; i <= 5; i++) {
      var imageObj = new Image();
      imageObj.src = "/images/gnabi_nav" + i + "on.jpg";
      imagePreloads.push(imageObj);
    }

    var indexArray = new Array(7,2,4,5);
    for (var i = 0; i < indexArray.length; i++) {
      for (var j = 1; j <= indexArray[i]; j++) {
        var imageObj = new Image();
        imageObj.src = "/images/gnabi_submenu" + (i + 1) + "_" + j + "on.gif";
        imagePreloads.push(imageObj);
      }
    }
    document.MM_p = imagePreloads;
  }
}