自定义窗体最大化时不盖住任务栏

还原有时有问题，不管了
        protected override void WndProc(ref Message m)
        {

            switch (m.Msg)
            {
                case WM_GETMINMAXINFO:

                    RECT area = new RECT();
                    SystemParametersInfo(SPI_GETWORKAREA, 0, ref area, 0);

                    MINMAXINFO info = (MINMAXINFO)m.GetLParam(typeof(MINMAXINFO));
                    info.ptMaxSize = new POINT(area.right, area.bottom);
                    info.ptMaxPosition = new POINT(0, 0);
                    info.ptMaxTrackSize = new POINT(area.right, area.bottom);
                    info.ptMinTrackSize = new POINT(100, 200);

                    Marshal.StructureToPtr(info, m.LParam, true);
                    m.Result = new IntPtr(0);       //must return 0;
                    return;
            }
           
            base.WndProc(ref m);

        }