var showing = [
	'2007apr7_021',
	'scan019',
	'scan006',
	'scan009'
];

var currentSet = 0;

function hidePhoto() {
	var shown = showing[currentSet];
	document.getElementById(shown).style.display = 'none';
	document.getElementById(shown + '_tn').style.borderColor = '#60404E';	
}

function showPhoto(name) {
	hidePhoto(currentSet);
	showThem(name);
	showing[currentSet] = name;
}

function showThem(name) {
	document.getElementById(name).style.display = 'inline';
	document.getElementById(name + '_tn').style.borderColor = '#A89978';	
}

function forwardSet() {
	hidePhoto();
	document.getElementById('set' + currentSet).style.display = 'none';
	++currentSet;
	document.getElementById('set' + currentSet).style.display = 'block';	
	showThem(showing[currentSet]);
	
	if (currentSet > 0) {
		document.getElementById('prevSet').style.visibility = 'visible';
	}
	if (currentSet + 1 >= showing.length) {
		document.getElementById('nextSet').style.visibility = 'hidden';
	}
}

function backSet() {
	hidePhoto();
	document.getElementById('set' + currentSet).style.display = 'none';
	--currentSet;
	document.getElementById('set' + currentSet).style.display = 'block';	
	showThem(showing[currentSet]);

	if (currentSet <= 0) {
		document.getElementById('prevSet').style.visibility = 'hidden';
	}
	if (currentSet + 1 < showing.length) {
		document.getElementById('nextSet').style.visibility = 'visible';
	}
}