<!--
var lastBox = -1;
var total = 0;

function showBox(index) {
	var e = 0;
	var boxes = document.getElementById('boxes');
	boxes = boxes.childNodes;
	
	total = 0;
	
	for (var i = 0; i < boxes.length; i++) {
		if (boxes[i].nodeName == 'DIV') {
			if (index == e) {
				boxes[i].style.display = 'block';
			} else {
				boxes[i].style.display = 'none';
			}
			e++;
			total++;
		}
	}
	
	lastBox = index;
}

function showNextBox() {
	showBox(lastBox + 1);
	_showBoxNav();
}

function showPreviousBox() {
	showBox(lastBox - 1);
	_showBoxNav();
}

function _showBoxNav() {
	var anterior = document.getElementById('anterior');
	var proxima = document.getElementById('proxima');

	if (lastBox < total - 1) {
		proxima.style.visibility = 'visible';
	} else {
		proxima.style.visibility = 'hidden';
	}
	if (lastBox == 0) {
		anterior.style.visibility = 'hidden';
	} else {
		anterior.style.visibility = 'visible';
	}
}

-->