BCGControlBar Pro for MFC
void CBCGPChartSeries::SetMarkerStrokeStyle ( const CBCGPStrokeStyle strokeStyle,
int  nDataPointIndex = -1 

Sets stroke style either for all series marker lines, or for specified data point.

Use this method to set stroke style for marker line. If nDataPointIndex is -1, the stroke style will be used for all data points that have not been formatted individually.

strokeStyleSpecifies the new stroke style.
nDataPointIndexSpecifies a data point index. Use -1 to set the option for a series.