img1 = new Image();
img2 = new Image();
img1.src = "../imgs/hover.gif";
img2.src = "../imgs/hover_off.gif"

var curElem="";
var curElem2="";

function hiddenLayer(elem, elem2) {
	document.getElementById(elem).style.visibility = 'hidden';
	if(elem2!="") document.getElementById(elem2).className='nav_cat';
}

function showLayer(elem, elem2) {
	if(curElem!="") hiddenLayer(curElem, curElem2);
	curElem=elem;
	curElem2=elem2;
	document.getElementById(elem).style.visibility = 'visible';
	if(elem2!="") document.getElementById(elem2).className='nav_cat_on';
}