code: function (e) {
  		var chart = this.chart;
  
  		// Record the start position
  		chart.mouseIsDown = e.type;
  		chart.cancelClick = false;
  		chart.mouseDownX = this.mouseDownX = e.chartX;
  		chart.mouseDownY = this.mouseDownY = e.chartY;
  	}
docs: Start a drag operation