ScreenToGif.Modern.WndProc C# (CSharp) Method

        protected override void WndProc(ref Message m)
        {
            if (_stage == Stage.Stopped || _stage == Stage.Editing)
            {
                if (m.Msg == (int)WM_NCHITTEST)
                {
                    #region Hit Test
                    // Trap WM_NCHITTEST
                    Point pos = new Point(m.LParam.ToInt32() & 0xffff, m.LParam.ToInt32() >> 16);
                    pos = this.PointToClient(pos);

                    //Bottom Left
                    if (pos.X <= cGrip && pos.Y >= this.ClientSize.Height - cGrip)
                    {
                        m.Result = (IntPtr)HitTest.HTBOTTOMLEFT;
                        return;
                    }

                    //Bottom Right
                    else if (pos.X >= this.ClientSize.Width - cGrip &&
                        pos.Y >= this.ClientSize.Height - cGrip)
                    {
                        m.Result = (IntPtr)HitTest.HTBOTTOMRIGHT;
                        return;
                    }

                    //Top Left
                    else if (pos.Y <= cBorder && pos.X <= cBorder)
                    {
                        m.Result = (IntPtr)HitTest.HTTOPLEFT;
                        return;
                    }

                    //Top Right
                    else if (pos.Y <= cBorder && pos.X >= this.ClientSize.Width - cBorder)
                    {
                        m.Result = (IntPtr)HitTest.HTTOPRIGHT;
                        return;
                    }

                    //Top
                    else if (pos.Y <= cBorder)
                    {
                        m.Result = (IntPtr)HitTest.HTTOP;
                        return;
                    }

                    //Caption
                    else if (pos.Y < cCaption && pos.X > 50 && pos.Y < ClientSize.Width)
                    {
                        m.Result = (IntPtr)HitTest.HTCAPTION;
                        return;
                    }

                    //Bottom
                    else if (pos.Y >= this.ClientSize.Height - cBorder)
                    {
                        m.Result = (IntPtr)HitTest.HTBOTTOM;
                        return;
                    }

                    //Left
                    else if (pos.X <= cBorder)
                    {
                        m.Result = (IntPtr)HitTest.HTLEFT;
                        return;
                    }

                    //Right
                    else if (pos.X >= this.ClientSize.Width - cBorder)
                    {
                        m.Result = (IntPtr)HitTest.HTRIGHT;
                        return;
                    }
                    #endregion
                }
            }

            base.WndProc(ref m);
        }