How to perform Google Maps regional based clustering or Marker Overlapping
<p>Here an example of <a href="http://jsfiddle.net/4mtyu/1833/"><code>OverlappingMarkerSpiderfier</code></a> by using Overlapping Marker Spiderfier  which is overlap markers based on their Distance, Is there any way to achieve same effect based on regions, for example all marker of a country overlap and show as a group of marker and after click on the same make that expand. </p>

<p>Edited </p>

<p>i have search stack overflow and google for possibilities but didn't found any solution, if any one have idea/fiddle  about how to  manually do the clustering with the marker manager which use polygon/region is also helpful.  </p>