const int HTLEFT = 10;
const int HTRIGHT = 11;
const int HTTOP = 12;
const int HTTOPLEFT = 13;
const int HTTOPRIGHT = 14;
const int HTBOTTOM = 15;
const int HTBOTTOMLEFT = 0x10;
const int HTBOTTOMRIGHT = 17;
protected override void WndProc(ref Message m)
{
 switch (m.Msg)
 {
  case 0x0084:
   base.WndProc(ref m);
   Point vPoint = new Point((int)m.LParam & 0xFFFF,
    (int)m.LParam >> 16 & 0xFFFF);
   vPoint = PointToClient(vPoint);
   if (vPoint.X <= 5)
    if (vPoint.Y <= 5)
     m.Result = (IntPtr)HTTOPLEFT;
    else if (vPoint.Y >= ClientSize.Height - 5)
     m.Result = (IntPtr)HTBOTTOMLEFT;
    else m.Result = (IntPtr)HTLEFT;
   else if (vPoint.X >= ClientSize.Width - 5)
    if (vPoint.Y <= 5)
     m.Result = (IntPtr)HTTOPRIGHT;
    else if (vPoint.Y >= ClientSize.Height - 5)
     m.Result = (IntPtr)HTBOTTOMRIGHT;
    else m.Result = (IntPtr)HTRIGHT;
   else if (vPoint.Y <= 5)
    m.Result = (IntPtr)HTTOP;
   else if (vPoint.Y >= ClientSize.Height - 5)
    m.Result = (IntPtr)HTBOTTOM;
   break;
  case 0x0201://鼠标左键按下的消息 
   m.Msg = 0x00A1;//更改消息为非客户区按下鼠标 
   m.LParam = IntPtr.Zero;//默认值 
   m.WParam = new IntPtr(2);//鼠标放在标题栏内 
   base.WndProc(ref m);
   break;
  default:
   base.WndProc(ref m);
   break;
 }
}