[C#] Resize Form with none border style

  protected override void WndProc(ref Message m) {
      if (m.Msg == 0x84) {  // Trap WM_NCHITTEST
        Point pos = new Point(m.LParam.ToInt32() & 0xffff, m.LParam.ToInt32() >> 16);
        pos = this.PointToClient(pos);
        if (pos.Y < cCaption) {
          m.Result = (IntPtr)2;  // HTCAPTION
          return;
        }
        if (pos.X >= this.ClientSize.Width - cGrip && pos.Y >= this.ClientSize.Height - cGrip) {
          m.Result = (IntPtr)17; // HTBOTTOMRIGHT
          return;
        }
      }
      base.WndProc(ref m);
    }