// onresize for ns4
var origWidth, origHeight;
if (document.layers) {
	origWidth = window.innerWidth; origHeight = window.innerHeight;
	window.onresize = function() { if (window.innerWidth != origWidth || window.innerHeight != origHeight) history.go(0); }
}


var cur_lyr;	// holds id of currently visible layer
var tab_on = 'tab_about';

function rotate(id, tab) {
	if (cur_lyr) hideLayer(cur_lyr);
	showLayer(id);
	cur_lyr = id;

	if (tab_on) taboff (tab_on);
	tabon ( tab );
	tab_on = tab;
}

function taboff ( tab ) {
	var t = document.getElementById(tab);
	t.className = 'off';
}

function tabon ( tab ) {
	var t = document.getElementById(tab);
	t.className = 'on';
}

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

function hideLayer(id) {
	var lyr = getElemRefs(id);
	if (lyr && lyr.css) { 
		lyr.css.display = "none";
	}
}

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;
}