var DURATION = 0.5;
var FPS = 10;
var PARAMS = { duration: DURATION, fps: FPS };
var PARAMS_IN  = { duration: DURATION, fps: FPS, from: 0.5, to: 1.0 };
var PARAMS_OUT = { duration: DURATION, fps: FPS, from: 1.0, to: 0.5 };

function parallel(arr) {
	return new Effect.Parallel(arr);
}

var states = new Array();

function showTag(tag) {
	return maybeTag(tag,'shown','hidden');
}

function hideTag(tag) {
	return maybeTag(tag,'hidden','shown');
}

function maybeTag(tag,shown,hidden) {
	if (!states[tag]) states[tag] = hidden;
	if (states[tag] != shown) {
		states[tag] = shown;
		return true;
	}
	return false;
}

function show(tag) {
	if (showTag(tag)) new Effect.Appear(tag,PARAMS);
}

function hide(tag) {
	if (hideTag(tag)) new Effect.Fade(tag,PARAMS);
}

function fadeIn(tag) {
		new Effect.Opacity(tag,PARAMS_IN);
}

function fadeOut(tag) {
	new Effect.Opacity(tag,PARAMS_OUT);
}

function appear(tag) {
	show(tag);
	fadeOut(tag);
}

/*function swapPage(newP) {
	if (newP == currentProductsPane) return;
	hidePage(currentPageType);
	showPage(newP);
	}

function hidePage(page) {
	hide('mainNavLeft_'+page);
}

var currentPageType;
function showPage(type) {
	currentPageType = type;
	show('mainNavLeft_'+type);
}
*/