BCGControlBar Pro for MFC
void CBCGPChartSeries::SetMarkerSize ( int  nSize,
int  nDataPointIndex = -1 

Sets marker size either for all markers in a series, or for specified data point.

Call this method to set data marker size either for all data points in a series if nDataPointIndex -1, or for specified by nDataPointIndex data point.

nSizeSpecifies the new size.
nDataPointIndexSpecifies a data point index. Use -1 to set the option for a series.