The ChartView is a code name for all the controls in the new Chart.dll. Part of the ChartView are the RadCartesianChart, RadPieChart, RadPolarChart, ChartDataSource. It seems that when you say ChartView you actually mean series, is this the case?
We do have tooltip template per series, so you should be able to get the behavior you need by setting the TooltipTemplate property of the series in mind. Let us know how it goes.
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