var lastRegionIndex = null;

function hideRegion() {
	var region = document.getElementById('i'+lastRegionIndex);
	region.style.visibility='hidden';
	return false;
}

function showRegion(regionIndex) {
	var region = document.getElementById('i'+regionIndex);
	lastRegionIndex = regionIndex;
	region.style.visibility='visible';
	return false;
}