SfDataGrid right click at StackedHeaderRow

VisualContainer visualContainer;

        void dataGrid_MouseRightButtonDown(object sender, MouseButtonEventArgs e)

        {

            var point = e.GetPosition(this.dataGrid);

            var propertyInfo = dataGrid.GetType().GetProperty("VisualContainer", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);

            visualContainer = propertyInfo.GetValue(dataGrid) as VisualContainer;

            var rowColumnIndex = visualContainer.PointToCellRowColumnIndex(point);

            var headerRowIndex = dataGrid.GetHeaderIndex();

            if (rowColumnIndex.RowIndex < headerRowIndex)

            {

                Window newWindow = new Window();

                newWindow.ShowDialog();

            }

        }