title: create InfoWindow for clustered markers using Google Maps v3
body: <p>I m developing a map that will cluster pins to prevent over crowded pin, but I wanted to create an infoWindow that will list all the marker when I click on the marker, I tried to get some help around and found out i can do it using marker.getTitle() but this is not helping me because I m using makrewithLable object and not using title, my question is there any why to add title to the marker or as I prefer to use the label instead to list them in the infowindow. 
  here is a copy of my work. </p>
  
  <pre><code>google.setOnLoadCallback(initialize);
  var globalMarker = [];
  var map;
  
    function initialize() {
      var center = new google.maps.LatLng(45.4214, -75.6919);
  
      map = new google.maps.Map(document.getElementById('map'), {
        zoom: 3,
        center: center,
        disableDoubleClickZoom: true,
        mapTypeId: google.maps.MapTypeId.ROADMAP
      });
  
      var markers = [];
      var infowindow = new google.maps.InfoWindow();
      for(i=0; i&lt;50; i++) {
      var latLng = new google.maps.LatLng(center.lat() + Math.random() - 0.5, center.lng() + Math.random() - 0.5);
      //var latLng = new google.maps.LatLng(45.4214, -75.6919)
       markers[i] = new MarkerWithLabel({
         position: latLng,
         draggable: true,
         raiseOnDrag: true,
         map: map,
         labelContent: "Marker ID = "+i,
         labelAnchor: new google.maps.Point(30, 0),
         labelClass: "labels", // the CSS class for the label
         labelStyle: {opacity: 0.75}
       });
        markers.push(markers);
      makeDiv(i, 15, "Marker #");
       google.maps.event.addListener(markers[i], 'click', function(e) {
      infowindow.setContent('Marker postion: '  + this.getPosition());
      infowindow.open(map, this);});
      }
      var clusterOptions = { zoomOnClick: false }
      var markerCluster = new MarkerClusterer(map, markers, clusterOptions);
      globalMarker = markers.slice();
      google.maps.event.addListener(markerCluster, 'clusterclick', function(cluster) {
  var content = '';
  
  // Convert lat/long from cluster object to a usable MVCObject
  var info = new google.maps.MVCObject;
  info.set('position', cluster.center_);
  
  //----
  //Get markers
  var markers = cluster.getMarkers();
  
  var titles = "";
  //Get all the titles
  for(var i = 0; i &lt; markers.length; i++) {
      titles += markers[i].getTitle() + "\n";
  }
  //----
  
  
  infowindow.close();
  infowindow.setContent(titles); //set infowindow content to titles
  infowindow.open(map, info);
  });
    }
  
    function makeDiv(index, zoomLevel, content) {
      document.getElementById("sidebar").innerHTML += '&lt;div onclick="zoomIn(' + index + ',' + zoomLevel + ')"&gt;' + content + ' ' + index + '&lt;/div&gt;';
    }
  
    function zoomIn(index, zoomLevel) {
      map.setCenter(globalMarker[index].getPosition());
      map.setZoom(zoomLevel);
    }
    google.maps.event.addDomListener(window, 'load', initialize);
  </code></pre>
  
  <p>Thank you </p>