var showPopUp = ""; 

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

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		inicio_over = newImage("images/inicio-over.gif");
		instituciones_over = newImage("images/instituciones-over.gif");
		galeria_over = newImage("images/galeria-over.gif");
		viajero_over = newImage("images/viajero-over.gif");
		contactos_over = newImage("images/contactos-over.gif");
		mapa_over = newImage("images/mapa-over.gif");
		preloadFlag = true;
	}
}

function viewFoto (url) {

	if(showPopUp  != ""){ 
		  showPopUp.close(); 
	}; 

	var w = 820;
	var h = 620;
	var winl = (screen.width - w) / 2;
    var wint = (screen.height - h) / 2;
    winprops = 'fullscreen=no,toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,'+'height='+h+',width='+w+',top='+wint+',left='+winl+'resizable=0'
	showPopUp = window.open(url,'blank',winprops);
}