// funzioni mostra/nascondi livello

	function newImage(arg) 
	{
	if (document.images) 
		{
		rslt = new Image();
		rslt.src = arg;
		return rslt;
		}
	}

	var preloadFlag = false;
	function preloadImages() 
	{
		if (document.images) 
		{

		motivo_	= newImage("img/motivo.gif");
		fondo_	= newImage("img/fondo.gif");
		coll01_ = newImage("img/coll01.gif");
		coll02_ = newImage("img/coll02.gif");
		coll03_ = newImage("img/coll03.gif");
		coll04_ = newImage("img/coll04.gif");
		coll05_ = newImage("img/coll05.gif");
		coll06_ = newImage("img/coll06.gif");
		coll07_ = newImage("img/coll07.gif");
		coll08_ = newImage("img/coll08.gif");
		coll09_ = newImage("img/coll09.gif");
		coll10_ = newImage("img/coll10.gif");
		coll11_ = newImage("img/coll11.gif");
		acco01_ = newImage("img/acco01.gif");
		acco02_ = newImage("img/acco02.gif");
		acco03_ = newImage("img/acco03.gif");

		preloadFlag = true;
		}
	}

	preloadImages();
	function showLayer(layerName)
	{
		if (preloadFlag) eval("document.getElementById('" + layerName + "').style.visibility = 'visible'");
	}

	function hideLayer(layerName)
	{
		if (preloadFlag) eval("document.getElementById('" + layerName + "').style.visibility = 'hidden'");
	}

	// funzioni aggiuntive 

	function apri(theURL,winName,features)
	{ window.open(theURL,winName,features); }


	function chiudi()
	{ this.close(); }

	function nulla(){}