title: Highstock/highcharts show multiple y-axis values in single tooltip
body: <p>I have a highstock chart with two y-axes.  When I mouseover the chart, the default tooltip only shows one of the y-axis, unless I directly put my mouse over the excluded series' point.  Is there a way to just show both y-axes in the tooltip at whatever x value the mouse is over in the chart?</p>