C#

protected override void OnPaint(PaintEventArgs pe)
{
	base.OnPaint(pe);
	if (ShowGrid && !this.DesignMode)
	{
		this.SuspendLayout();
		Graphics g = pe.Graphics;
		Pen pen = new Pen(Color.Black, 1);
		pen.DashStyle = DashStyle.Dot;
		Point p1 = new Point(0,0);
		Point p2 = new Point(0,0);
		for (int x = BorderSize.Width; x < this.Size.Width - BorderSize.Width; x += GridSize.Width)
		{
			p1.X = x; p1.Y = BorderSize.Height;
			p2.X = x; p2.Y = this.Size.Height - BorderSize.Height;
			g.DrawLine(pen, p1, p2);
		}
		for (int y = BorderSize.Height; y < this.Size.Height - BorderSize.Height; y += GridSize.Height)
		{
			p1.X = BorderSize.Width; p1.Y = y;
			p2.X = this.Size.Width - BorderSize.Width; p2.Y = y;
			g.DrawLine(pen, p1, p2);
		}
		this.ResumeLayout();
	}
}