// JavaScript Document

function showOverlay(city, isOn) {
	if (isOn) {
		document.getElementById('sydney').style.visibility='hidden';	
		document.getElementById('melbourne').style.visibility='hidden';	
		document.getElementById('brisbane').style.visibility='hidden';		
		document.getElementById('close').style.visibility='hidden';
		document.getElementById('blackPanel').style.visibility='hidden';		
	} else {
		document.getElementById(city).style.visibility='visible';	
		document.getElementById('close').style.visibility='visible';	
		document.getElementById('blackPanel').style.visibility='visible';
	}
}