function preLoadImages() {
	imagesArray = new Array();
	n = 0;
	if (document.images) {
		for (i=0; i<document.images.length; i++) {
			if (document.images[i].src.indexOf("_n.jpg")>0) { 
				img_on = document.images[i].src;
				img_on = img_on.substring(0,img_on.length-5) + "h.jpg";
				imagesArray[n] = new Image();
				imagesArray[n].src = document.images[i].src;
				imagesArray[n+1] = new Image();
				imagesArray[n+1].src = img_on; 
				n = n+2;
			}
		}
	}
}

var sMenuState = "none";

function showHideMenu() {
	if (sMenuState == "none") {
		sMenuState = "block";
	} else {
		sMenuState = "none";
	}
	document.getElementById("nav_items").style.display = sMenuState;
}

function hideItem(itemID) {
	imgName = itemID.replace(/item/gi, "image");
	if (document.images) {
		img_on = document.images[imgName].src;
		document.images[imgName].src = img_on.substring(0,img_on.length-5) + "n.jpg";
	}
}

function showItem(itemID) {
	imgName = itemID.replace(/item/gi, "image");
	if (document.images) {	
		img_on = document.images[imgName].src;
		document.images[imgName].src = img_on.substring(0,img_on.length-5) + "h.jpg";
	}
}

document.onclick = function() {
	sMenuState = "none";
	document.getElementById("nav_items").style.display = sMenuState;
}