[转]C#改变无边框窗体大小

       #region 改变窗体大小
        const int WM_NCHITTEST = 0x0084;
        const int HTLEFT = 10;    //左边界
        const int HTRIGHT = 11;   //右边界
        const int HTTOP = 12; //上边界
        const int HTTOPLEFT = 13; //左上角
        const int HTTOPRIGHT = 14;    //右上角
        const int HTBOTTOM = 15;  //下边界
        const int HTBOTTOMLEFT = 0x10;    //左下角
        const int HTBOTTOMRIGHT = 17; //右下角

        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            switch (m.Msg)
            {
                case WM_NCHITTEST:
                {
                    Point vPoint = new Point((int)m.LParam & 0xFFFF,(int)m.LParam >> 16 & 0xFFFF);
                    vPoint = PointToClient(vPoint);
                    //判断：仅当当前窗体状态不是最大化时，相关鼠标事件生效
                    if (this.WindowState != FormWindowState.Maximized)
                    {
                        if (vPoint.X < 10)
                        {
                            if (vPoint.Y < 10)
                            {
                                m.Result = (IntPtr)HTTOPLEFT;
                            }
                            else if (vPoint.Y > this.Height - 10)
                            {
                                m.Result = (IntPtr)HTBOTTOMLEFT;
                            }
                            else
                            {
                                m.Result = (IntPtr)HTLEFT;
                            }
                        }
                        else if (vPoint.X > this.Width - 10)
                        {
                            if (vPoint.Y < 10)
                            {
                                m.Result = (IntPtr)HTTOPRIGHT;
                            }
                            else if (vPoint.Y > this.Height - 10)
                            {
                                m.Result = (IntPtr)HTBOTTOMRIGHT;
                            }
                            else
                            {
                                m.Result = (IntPtr)HTRIGHT;
                            }
                        }
                        else if (10 < vPoint.X && vPoint.X < this.Width - 10)
                        {
                            if (vPoint.Y < 10)
                            {
                                m.Result = (IntPtr)HTTOP;
                            }
                            else if (vPoint.Y > this.Height - 10)
                            {
                                m.Result = (IntPtr)HTBOTTOM;
                            }
                        }
                    }
                    break;
                }
            }
        }
        #endregion

将窗体的Padding中将所有的值，均设为1即可（或更大，只要不为0就行。当然，数值越大，也意味着窗体四周的“露白”越多，同时，在调整大小时，也会越容易被鼠标“捕捉”到。一般来说，窗体的左、右边框容易被捕捉

转自：http://www.beijibear.com/article/10-09/cheongyuhin5.html