public partial class Form1 : Form{    [DllImport("Gdi32.dll", EntryPoint = "CreateRoundRectRgn")]    private static extern IntPtr CreateRoundRectRgn    (        int nLeftRect, // x-coordinate of upper-left corner        int nTopRect, // y-coordinate of upper-left corner        int nRightRect, // x-coordinate of lower-right corner        int nBottomRect, // y-coordinate of lower-right corner        int nWidthEllipse, // height of ellipse        int nHeightEllipse // width of ellipse     );            [DllImport("dwmapi.dll")]    public static extern int DwmExtendFrameIntoClientArea(IntPtr hWnd, ref MARGINS pMarInset);    [DllImport("dwmapi.dll")]    public static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int attrValue, int attrSize);    [DllImport("dwmapi.dll")]    public static extern int DwmIsCompositionEnabled(ref int pfEnabled);    private bool m_aeroEnabled;                     // variables for box shadow    private const int CS_DROPSHADOW = 0x00020000;    private const int WM_NCPAINT = 0x0085;    private const int WM_ACTIVATEAPP = 0x001C;    public struct MARGINS                           // struct for box shadow    {        public int leftWidth;        public int rightWidth;        public int topHeight;        public int bottomHeight;    }    private const int WM_NCHITTEST = 0x84;          // variables for dragging the form    private const int HTCLIENT = 0x1;    private const int HTCAPTION = 0x2;    protected override CreateParams CreateParams    {        get        {            m_aeroEnabled = CheckAeroEnabled();            CreateParams cp = base.CreateParams;            if (!m_aeroEnabled)                cp.ClassStyle |= CS_DROPSHADOW;            return cp;        }    }    private bool CheckAeroEnabled()    {        if (Environment.OSVersion.Version.Major >= 6)        {            int enabled = 0;            DwmIsCompositionEnabled(ref enabled);            return (enabled == 1) ? true : false;        }        return false;    }    protected override void WndProc(ref Message m)    {        switch (m.Msg)        {            case WM_NCPAINT:                        // box shadow                if (m_aeroEnabled)                {                    var v = 2;                    DwmSetWindowAttribute(this.Handle, 2, ref v, 4);                    MARGINS margins = new MARGINS()                    {                        bottomHeight = 1,                        leftWidth = 1,                        rightWidth = 1,                        topHeight = 1                    };                    DwmExtendFrameIntoClientArea(this.Handle, ref margins);                }                break;            default:                break;        }        base.WndProc(ref m);        if (m.Msg == WM_NCHITTEST && (int)m.Result == HTCLIENT)     // drag the form            m.Result = (IntPtr)HTCAPTION;    }    public Form1()    {        m_aeroEnabled = false;        this.FormBorderStyle = FormBorderStyle.None;        InitializeComponent();    }}