Windows Form - Mudar a Cor da Borda de um GroupBox

Para mudar as propriedade s de bordas em um Windows Form você precisará criar um evento Paint e criar um método para esta classe, conforme mostra o exemplo abaixo.


private void gbxProcessoTecnica_Paint(object sender, PaintEventArgs e)
        {
            GroupBox box = sender as GroupBox;
            DrawGroupBox(box, e.Graphics, Color.Red, Color.Blue, Color.White);
        }

private void DrawGroupBox(GroupBox box, Graphics g, Color textColor, Color borderColor, Color backgroundColor)
        {
            if (box != null)
            {
                Brush textBrush = new SolidBrush(textColor);
                Brush borderBrush = new SolidBrush(borderColor);
                Pen borderPen = new Pen(borderBrush);
                SizeF strSize = g.MeasureString(box.Text, box.Font);
                Rectangle rect = new Rectangle(box.ClientRectangle.X,
                                               box.ClientRectangle.Y + (int)(strSize.Height / 2),
                                               box.ClientRectangle.Width - 1,
                                               box.ClientRectangle.Height - (int)(strSize.Height / 2) - 1);

                // Coloque a cor do background aqui
                g.Clear(backgroundColor);

                // Draw text
                g.DrawString(box.Text, box.Font, textBrush, box.Padding.Left, 0);

                // Drawing Border
                //Left
                g.DrawLine(borderPen, rect.Location, new Point(rect.X, rect.Y + rect.Height));
                //Right
                g.DrawLine(borderPen, new Point(rect.X + rect.Width, rect.Y), new Point(rect.X + rect.Width, rect.Y + rect.Height));
                //Bottom
                g.DrawLine(borderPen, new Point(rect.X, rect.Y + rect.Height), new Point(rect.X + rect.Width, rect.Y + rect.Height));
                //Top1
                g.DrawLine(borderPen, new Point(rect.X, rect.Y), new Point(rect.X + box.Padding.Left, rect.Y));
                //Top2
                g.DrawLine(borderPen, new Point(rect.X + box.Padding.Left + (int)(strSize.Width), rect.Y), new Point(rect.X + rect.Width, rect.Y));
            }
        }