Add support for tooltip visualization over the continuous series segments that would interpolate the actual value between data points. XAML Team reviewed this request and decided not to address it in the future. Appropriate way to get this is to use the crosshair behavior.
UPD. I don't want the value to be interpolated between nearest data points, I want the tooltip to show the value of the closest data point. This is the way it works in Infragistics chart.
Yes, this would be really great! That's the reason why I'm still using chart from other company's frameworks and can't use Telerik chart...