Thanks for writing.
You need to create a class that inherits from ChartTrackballContentAdapter.
Then you need to override the appropriate create method. Assuming you have a categorical chart with line or bar series, you need to override the createCategoricalDataPointView method.
In this method your have to create a view that will visualize the value of the given data point.
Then when your class is ready you need to tell the trackball to use it. You can do this by calling
Please write again if you have more questions.
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.