[Solved]-Tooltip for whole stack in grouped stacked Highcharts diagram-Highcharts

You can use tooltip formatter and then find points.

tooltip: {
        formatter: function () {
            var indexS = this.series.index,
                indexP = this.point.x,
                series = this.series.chart.series,
                out = 'y1:' + this.y + '<br/>';

            switch (indexS) {
                case 0:
                    out += 'y2: ' + series[1].data[indexP].y;
                    break;
                case 1:
                     out += 'y2: ' +series[0].data[indexP].y;
                    break;
                case 2:
                     out += 'y2: ' +series[3].data[indexP].y;
                    break;
                case 3:
                     out += 'y2: ' + series[2].data[indexP].y;
                    break;
            }

            return out;
        }
   },

http://jsfiddle.net/3Utat/10/