If you have not yet integrated the RadChart deeply into your application I will suggest that you migrate to our new RadChartView
. It is a newer control with a higher performance
rate and is generally more powerful flexible.
I am unsure if I understand you fully. Do you mean that (if you have line series) you need to drag and move the points of the chart? I have attached a simple project to demonstrate this (note that the project is WPF but the same is applicable for SL).
the Telerik team