Highmaps: putting border around a category of area

Question

I am using higmaps to show category of data like this:

HighChart Code:

http://jsfiddle.net/gh/get/jquery/1.9.1/highslide-software/highcharts.com/tree/master/samples/maps/demo/category-map/

But I want to be able to show border around a category of areas, that will demarcate a set of areas from other. I do not want border around each state.

Thanks in advance.

Answer 1

what you are after might be acquired by passing borderWidth: 0 to the elements in a series. See this JSFiddle.