Show data when Google Maps marker is clicked in markercluster - google-maps-api-3

Question

I am trying to work out how to show custom data when a Google Maps markerclusterer marker is clicked but can't find this documented anywhere.
My markerclusterer code looks like this but my attempt at capturing the click event on a marker is not working:
var markerClusterer = null;
var map = null;
var imageUrl = 'http://chart.apis.google.com/chart?cht=mm&chs=24x32&' +
'chco=FFFFFF,008CFF,000000&ext=.png';
google.maps.event.addDomListener(window, 'load', initialize);
function refreshMap() {
if (markerClusterer) {
markerClusterer.clearMarkers();
}
var markers = [];
var markerImage = new google.maps.MarkerImage(imageUrl,
new google.maps.Size(24, 32));
/*
for (var i = 0; i < 1000; ++i) {
var latLng = new google.maps.LatLng(data.photos[i].latitude,
data.photos[i].longitude)
var marker = new google.maps.Marker({
position: latLng,
icon: markerImage
});
markers.push(marker);
}
*/
for (var i = 0; i < numItemsToShow; ++i) {
var latLng = new google.maps.LatLng(itemsToShow[i].lat, itemsToShow[i].long);
var marker = new google.maps.Marker({
position: latLng,
icon: markerImage
});
markers.push(marker);
}
var zoom = parseInt(document.getElementById('zoom').value, 10);
var size = parseInt(document.getElementById('size').value, 10);
var style = parseInt(document.getElementById('style').value, 10);
zoom = zoom == -1 ? null : zoom;
size = size == -1 ? null : size;
style = style == -1 ? null: style;
markerClusterer = new MarkerClusterer(map, markers, {
maxZoom: zoom,
gridSize: size,
styles: styles[style]
});
}
function initialize() {
map = new google.maps.Map(document.getElementById('map'), {
zoom: 2,
center: new google.maps.LatLng(39.91, 116.38),
mapTypeId: google.maps.MapTypeId.ROADMAP,
//styles: [{"featureType":"administrative","elementType":"labels.text.fill","stylers":[{"color":"#444444"}]},{"featureType":"administrative.land_parcel","elementType":"all","stylers":[{"visibility":"off"}]},{"featureType":"landscape","elementType":"all","stylers":[{"color":"#f2f2f2"}]},{"featureType":"landscape.natural","elementType":"all","stylers":[{"visibility":"off"}]},{"featureType":"poi","elementType":"all","stylers":[{"visibility":"on"},{"color":"#052366"},{"saturation":"-70"},{"lightness":"85"}]},{"featureType":"poi","elementType":"geometry.fill","stylers":[{"saturation":"-100"},{"lightness":"0"}]},{"featureType":"poi","elementType":"labels","stylers":[{"visibility":"simplified"},{"lightness":"-53"},{"weight":"1.00"},{"gamma":"0.98"}]},{"featureType":"poi","elementType":"labels.text","stylers":[{"visibility":"off"}]},{"featureType":"poi","elementType":"labels.icon","stylers":[{"visibility":"off"},{"lightness":"0"}]},{"featureType":"poi.park","elementType":"geometry.fill","stylers":[{"hue":"#3dff00"},{"saturation":"-100"}]},{"featureType":"road","elementType":"all","stylers":[{"saturation":-100},{"lightness":45},{"visibility":"on"}]},{"featureType":"road","elementType":"geometry","stylers":[{"saturation":"-18"}]},{"featureType":"road","elementType":"labels","stylers":[{"visibility":"off"}]},{"featureType":"road.highway","elementType":"all","stylers":[{"visibility":"on"}]},{"featureType":"road.arterial","elementType":"all","stylers":[{"visibility":"on"}]},{"featureType":"road.arterial","elementType":"labels.icon","stylers":[{"visibility":"off"}]},{"featureType":"road.local","elementType":"all","stylers":[{"visibility":"on"}]},{"featureType":"road.local","elementType":"labels.text","stylers":[{"visibility":"off"}]},{"featureType":"transit","elementType":"all","stylers":[{"visibility":"off"}]},{"featureType":"water","elementType":"all","stylers":[{"color":"#57677a"},{"visibility":"on"}]},{"featureType":"water","elementType":"geometry.fill","stylers":[{"lightness":"40"}]}]
styles: [{"featureType":"water","stylers":[{"visibility":"on"},{"color":"#b5cbe4"}]},
{"featureType":"landscape","stylers":[{"color":"#efefef"}]},
{"featureType":"road.highway","elementType":"geometry","stylers":[{"color":"#83a5b0"}]},
{"featureType":"road.arterial","elementType":"geometry","stylers":[{"color":"#bdcdd3"}]},
{"featureType":"road.local","elementType":"geometry","stylers":[{"color":"#ffffff"}]},
{"featureType":"poi.park","elementType":"geometry","stylers":[{"color":"#e3eed3"}]},
{"featureType":"administrative","stylers":[{"visibility":"on"},{"lightness":33}]},
{"featureType":"road"},
{"featureType":"poi.park","elementType":"labels","stylers":[{"visibility":"on"},{"lightness":20}]},{},
{"featureType":"road","stylers":[{"lightness":20}]}]
});
var refresh = document.getElementById('refresh');
google.maps.event.addDomListener(refresh, 'click', refreshMap);
var clear = document.getElementById('clear');
google.maps.event.addDomListener(clear, 'click', clearClusters);
google.maps.event.addListener(markerClusterer, 'click', function () {
// do something with this marker ...
this.setTitle('I am clicked');
});
refreshMap();
}
function clearClusters(e) {
e.preventDefault();
e.stopPropagation();
markerClusterer.clearMarkers();
}

Answer 1

This works for me (it opens an infowindow when you mouseover the cluster icon, if you click on the cluster icon, the default behavior is to zoom to the cluster bounds, which makes it hard to see the change of the tooltip/title on the cluster icon):
var infoWindow = new google.maps.InfoWindow();
google.maps.event.addListener(markerClusterer, 'mouseover', function (cluster) {
// do something with this cluster ...
infoWindow.setContent("Mouseover<br>"+cluster.getCenter().toUrlValue());
infoWindow.setPosition(cluster.getCenter());
infoWindow.open(map);
});