title: Change style of selected cluster using MarkerClusterer
body: <p>I have flowing situation. There are some markers on map that are on exactly the same lat/lng so MarkerClusterer zooming do not break cluster. I handled users click, but I would like to set different image for clicked cluster.</p>
  
  <p>I found <code>setStyles()</code> method but that one changes default style set for cluster generation.</p>
  
  <p>I tried something along these lines:</p>
  
  <pre><code>markerCluster = new MarkerClusterer(map, duplicateMarkers);
  markerCluster.clusters_[0].clusterIcon_.url_ = imageurl;
  </code></pre>
  
  <p>I set different image but it does't change on map, also tried puting in in <code>setTimeout</code>.</p>