Alsing.Windows.Forms.CoreLib.SplitViewControl.Horizontal_MouseMove C# (CSharp) Метод

        private void Horizontal_MouseMove(object sender, MouseEventArgs e)
        {
            if (Action == SizeAction.SizeH && e.Button == MouseButtons.Left)
            {
                Point start;
                int x = e.X;
                int y = e.Y;


                if (y + Horizontal.Top > Height - 4)
                    y = Height - 4 - Horizontal.Top;
                if (y + Horizontal.Top < 0)
                    y = 0 - Horizontal.Top;

                if (!FirstTime)
                {
                    start = PointToScreen(Location);
                    start.Y += PrevPos.Y + Horizontal.Location.Y;
                    ControlPaint.FillReversibleRectangle(new Rectangle(start.X, start.Y, Width, 3), Color.Black);
                }
                else
                    FirstTime = false;

                start = PointToScreen(Location);
                start.Y += y + Horizontal.Location.Y;
                ControlPaint.FillReversibleRectangle(new Rectangle(start.X, start.Y, Width, 3), Color.Black);

                PrevPos = new Point(x, y);
            }
        }