C#更改groupbox边框颜色

private void groupBox1_Paint(object sender, PaintEventArgs e)
        {
            e.Graphics.Clear(groupBox1.BackColor);
            e.Graphics.DrawString(groupBox1.Text, groupBox1.Font, Brushes.Red, 10, 1);
            e.Graphics.DrawLine(Pens.Red, 1, 7, 8, 7);
            e.Graphics.DrawLine(Pens.Red, e.Graphics.MeasureString(groupBox1.Text, groupBox1.Font).Width + 8, 7, groupBox1.Width - 2, 7);
            e.Graphics.DrawLine(Pens.Red, 1, 7, 1, groupBox1.Height - 2);
            e.Graphics.DrawLine(Pens.Red, 1, groupBox1.Height - 2, groupBox1.Width - 2, groupBox1.Height - 2);
            e.Graphics.DrawLine(Pens.Red, groupBox1.Width - 2, 7, groupBox1.Width - 2, groupBox1.Height - 2); 
        }