function swapLayers(id) {
	var cur_lyr; // holds id of currently visible layer

	if (cur_lyr) hideLayer(cur_lyr);
	showLayer(id);
	cur_lyr = id;
}

function showLayer(id) {
	var lyr = getElemRefs(id);
	if (lyr && lyr.css) lyr.css.visibility = "visible";
}

function hideLayer(id) {
	var lyr = getElemRefs(id);
	if (lyr && lyr.css) lyr.css.visibility = "hidden";
}

function getElemRefs(id) {
	var el = (document.getElementById) ? document.getElementById(id) : (document.all) ? document.all[id] : (document.layers) ? document.layers[id] : null;
	if (el) el.css = (el.style) ? el.style : el;
	return el;
}