title: infowindow is not closing when close button is pressed in google maps v3 markercluster..?
body: <p><strong>load function</strong></p>
  
  <pre><code>function load() {
  
                   var cluster = [];
                  infoWindow = new google.maps.InfoWindow();         
  
                   var map = new google.maps.Map(document.getElementById("map"), {
                          center: new google.maps.LatLng(10.6145, -24.3418),
                          zoom: 2,
                          mapTypeId: 'roadmap'
                        });
  
  
                // Read the data from example.xml
                 downloadUrl("phpsqlajax_genxml.php", function(data) {
                  var xml = data.responseXML;
                  var markers = xml.documentElement.getElementsByTagName("marker");
  
                  for (var i = 0; i &lt; markers.length; i++) {
                    // obtain the attribues of each marker
                    var name = markers[i].getAttribute("name");
                    var address = markers[i].getAttribute("address");
                    var link = markers[i].getAttribute("link");
                    var type = markers[i].getAttribute("type");
                    var point = new google.maps.LatLng(
                        parseFloat(markers[i].getAttribute("lat")),
                        parseFloat(markers[i].getAttribute("lng")));
  
                     var html = "&lt;b&gt;" + '&lt;a href="' + link + '" &gt;' + markers[i].getAttribute("name")  + '&lt;/a&gt;' + "&lt;/b&gt; &lt;br/&gt;"  + "&lt;/b&gt; &lt;br/&gt;" + '&lt;a href="' + link + '" &gt;' + markers[i].getAttribute("address")  + '&lt;/a&gt;';
  
                    var icon = customIcons[type] || {};
  
                    // create the marker
                      var marker = new google.maps.Marker({
                      map: map,
                      position: point,
                      icon: icon.icon,
                      shadow: icon.shadow
                    });
  
  
                   addMarker(marker, html);
  
  
  
                cluster.push(marker);
  
                  }
                  var mc = new MarkerClusterer(map,cluster);
  
                   //markerCluster = new MarkerClusterer(map, gmarkers);
                });
     }
  </code></pre>
  
  <p><strong>add markers</strong></p>
  
  <pre><code>function addMarker(marker, content)
      {
  
  
        google.maps.event.addListener(marker, 'click', function() {
  
         infoWindow.setContent(content);
         infoWindow.open(map, marker);
         infoWindow.close();
  
  
       });
  
      }
  </code></pre>
  
  <p><em>code for ajax</em></p>
  
  <pre><code>function downloadUrl(url, callback) {
    var request = window.ActiveXObject ?
        new ActiveXObject('Microsoft.XMLHTTP') :
        new XMLHttpRequest;
  
    request.onreadystatechange = function() {
      if (request.readyState == 4) {
        request.onreadystatechange = doNothing;
        callback(request, request.status);
      }
    };
  
    request.open('GET', url, true);
    request.send(null);
  }
  </code></pre>