How can I create faded edges for a form in C# .NET using linear gradient brush?

Question

I got this code from ChatGPT but it's not working.

this.BackColor = Color.FromArgb(0, Color.Magenta); // Set the form's background color with an alpha value of 0
this.TransparencyKey = Color.Magenta; // Set the same color as the transparency key

protected override void OnPaint(PaintEventArgs e)
{
    base.OnPaint(e);

    // Create a linear gradient brush for the faded edges
    using (var brush = new System.Drawing.Drawing2D.LinearGradientBrush(
        new Point(0, 0),
        new Point(this.Width, this.Height),
        Color.FromArgb(0, Color.White), // Start with a transparent color
        Color.White)) // End with an opaque white color
    {
        // Create a graphics path representing the entire form
        using (var path = new GraphicsPath())
        {
            path.AddRectangle(new Rectangle(0, 0, this.Width, this.Height));
            path.CloseFigure();

            // Set the clipping region to exclude the transparent form area
            e.Graphics.SetClip(path, CombineMode.Exclude);

            // Fill the clipped region with the gradient brush
            e.Graphics.FillPath(brush, path);
        }
    }
}

I did the first code in form disigner but the second code is not working.