ElementStacks

HTML

<script src="http://highcharts.com/js/testing.js"></script>
<div id="container" style="height: 400px; width: 500"></div>

JavaScript

var chart = new Highcharts.Chart({
    chart: {
        renderTo: 'container',
        type: 'pie'
    },
    
    plotOptions: {
        pie: {
            point: {
                events: {
                    legendItemClick: function () {
                        alert("do something here");
                        return false; // <== returning false will cancel the default action
                    }
                }
            },
            showInLegend: true
        }
    },
    
    series: [{
        data: [
            ['Firefox',   44.2],
            ['IE7',       26.6],
            ['IE6',       20],
            ['Chrome',    3.1],
            ['Other',    5.4]
        ]
    }]
});