I am using highcharts ( Line ) in my php application. I want to use onclick event handler inside the tooltip to open the modal dialog. But i don't find any solution for that, even in highcharts there is no click event available for tooltip item. I also used formatter option inside tooltip but it doesn't worked. Please help me in this issue

I am trying this

tooltip: {
useHtml: true,
formatter: function () {
var s = '<b>' + this.x + '</b>';
$.each(this.points, function (i, point) {
s += '<br/><span style="color:' + point.series.color + '">\u25CF</span>\n\ <span onclick="my_function();">Click Me</span> ' + point.series.name + ': ' + point.y;
});
return s;
},
shared: true
}

but my_function is not calling when i click on "Click Me"