Code

void flow_MouseClick(object sender, MouseEventArgs e)
        {

                FlowChart flow = (FlowChart)sender;
                Grid grid = flow.LaneGrid;

                PointF clickPosition = e.Location; //click's position
                RectangleF rec = RectangleF.Empty;
                ICell cell = grid.GetCellFromPoint(clickPosition, ref rec);
                int indexSelectedLane = grid.GetCellRow(cell);
                if (indexSelectedLane >= 0)
                {
                    string formatoTesto = "Arial";
                    grid.RowHeaders[indexSelectedLane ].TitleFont = new System.Drawing.Font(formatoTesto, 8, System.Drawing.FontStyle.Bold);
                 }

            }