Currently, if the trackball position is outside the plot area boundaries, the element is not clipped and there is no mechanism that allows clipping it. 

Note: The trackball is the small ellipse that snaps to the data points.

Currently the MouseWheel event used to zoom is not handled which means that the event will bubble to the parent elements which can lead to scrolling issues. Add an option to handle the MouseWheel event when the chart zooming is enabled.

To get the desired result, you can handle the MouseWheel event of the chart manually.

 private void RadCartesianChart_MouseWheel(object sender, MouseWheelEventArgs e)
 {
     e.Handled = true;
 }