private int WM_SYSCOMMAND = 0x112;
private long SC_MAXIMIZE = 0xF030;
private long SC_MINIMIZE = 0xF020;
private long SC_CLOSE = 0xF060;
protected override void WndProc(ref Message m)
{
    if (m.Msg == WM_SYSCOMMAND)
    {
        if (m.WParam.ToInt64() == SC_MAXIMIZE)
        {
            //MessageBox.Show("MAXIMIZE ");
            return;
        }
        if (m.WParam.ToInt64() == SC_MINIMIZE)
        {
            //MessageBox.Show("MINIMIZE ");
            return;
        }
        if (m.WParam.ToInt64() == SC_CLOSE)
        {
            //MessageBox.Show("CLOSE ");
            return;
        }
    }
    base.WndProc(ref m);
}