Form Shadow

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private const int CS_DROPSHADOW = 0x00020000;

    protected override CreateParams CreateParams
    {
        get
        {
            CreateParams p = base.CreateParams;
            p.ClassStyle |= CS_DROPSHADOW;
            return p;
        }
    }
}