var page = null;

function initNav(id) {
	// Set the image that should be ON always.
	page = id;
	mouseOn(page);
}
function mouseOn(id) {
	document.getElementById(id).src = 'images/navOn-' + id + '.png';
}
function mouseOff(id) {
	if (id != page) {
		document.getElementById(id).src = 'images/navOff-' + id + '.png';
	}
}