ElementStacks

HTML

<script src="http://code.highcharts.com/2.2.4/highcharts.js"></script>
<div id="container" style="height: 400px"></div>

CSS

.highcharts-axis {
 cursor: pointer;   
}

JavaScript

var chart = new Highcharts.Chart({
    chart: {
        renderTo: 'container',
        marginRight: 80 // like left
    },
    xAxis: {
        categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    },
    yAxis: [{
        lineWidth: 1,
        title: {
            text: 'Secondary Axis'
        }
    }],
    
    series: [{
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4]        
    }]
});

var clearSelection = function() { $('.highcharts-axis').css('stroke', ''); };

$('.highcharts-axis').click(function(event) {
    clearSelection();
    $(this).css('stroke', 'green');
    return false;
});
$(document).click(clearSelection);
$('svg').click(clearSelection);