if (document.images){
	aboutOn = new Image();
	aboutOn.src = "pic/nav_about_hover.png";

	aboutOff = new Image();
	aboutOff.src = "pic/nav_about.png";
				
	portfolioOn = new Image();
	portfolioOn.src = "pic/nav_portfolio_hover.png";

	portfolioOff = new Image();
	portfolioOff.src = "pic/nav_portfolio.png";
				
	photosOn = new Image();
	photosOn.src = "pic/nav_photos_hover.png";

	photosOff = new Image();
	photosOff.src = "pic/nav_photos.png";
				
	gamemapsOn = new Image();
	gamemapsOn.src = "pic/nav_gamemaps_hover.png";
				
	gamemapsOff = new Image();
	gamemapsOff.src = "pic/nav_gamemaps.png";
}

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");
	}
}

//Modified version of http://javascript-array.com/scripts/simple_drop_down_menu/

var timeout	= 500;
var closetimer	= 0;
var ddmenuitem	= 0;

// open hidden layer
function mopen(id)
{	
	// cancel close timer
	mcancelclosetime();

	// close old layer
	if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';

	// get new layer and show it
	ddmenuitem = document.getElementById(id);
	ddmenuitem.style.visibility = 'visible';

}
// close showed layer
function mclose()
{
	if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';
}

// go close timer
function mclosetime()
{
	closetimer = window.setTimeout(mclose, timeout);
}

// cancel close timer
function mcancelclosetime()
{
	if(closetimer)
	{
		window.clearTimeout(closetimer);
		closetimer = null;
	}
}

// close layer when click-out
document.onclick = mclose;