I know that each axis in QCustomPlot has two kinds of grids,one called grid and another called subgrid. Each kinds of grid has its own QPen,this means all gird has the same QPen and subgrid also.Then how can i set different color for different grid?

ui->customPlot->xAxis->grid()->setPen(QPen(QColor(140, 0, 0), 1, Qt::SolidLine)); // set QPen for grid ui->customPlot->xAxis->grid()->setSubGridPen(QPen(QColor(80, 80, 80), 1, Qt::DotLine)); // set QPen for //subgrid,so how can i set third color for some grid?