ScreenSaver.ScreenSaverForm.ScreenSaverForm_MouseDown C# (CSharp) Method

        private void ScreenSaverForm_MouseDown(object sender, MouseEventArgs e)
        {
            Point m = PointToClient(Cursor.Position);
            var drag = 12;
            bool? toTop = m.Y < drag ? true : (m.Y > (Size.Height - drag) ? false : (bool?)null);
            bool? toLeft = m.X < drag ? true : (m.X > (Size.Width - drag) ? false : (bool?)null);

            if (e.Button == MouseButtons.Left)
            {
                if (toTop == null && toLeft == null)
                    NativeMethods.DragWindow(Handle);
                else
                    NativeMethods.ResizeWindow(Handle, toTop, toLeft);
            }
        }