in widgets/distribution-reports/src/app/nv-flex-pie-chart.js [561:569]
var showTooltip = function(e, offsetElement) {
var tooltipLabel = pie.description()(e.point) || pie.x()(e.point);
var left = e.pos[0] + margin.left + ( (offsetElement && offsetElement.offsetLeft) || 0 ),
top = e.pos[1] + margin.top + ( (offsetElement && offsetElement.offsetTop) || 0),
y = pie.valueFormat()(pie.y()(e.point)),
content = tooltipContent(tooltipLabel, y, e, chart);
nv.tooltip.show([left, top], content, e.gravity, 0, offsetElement);
};