WinForms StackPanel (Top to Bottom only)

StackPanel.cs

    public class StackPanel : Panel
    {
        private LayoutEngine _engine;

        public StackPanel()
        {
            HorizontalScroll.Maximum = 0;
            AutoScroll = false;
            VerticalScroll.Visible = false;
            AutoScroll = true;
        }


        public override LayoutEngine LayoutEngine => _engine ??= new StackLayout();


        class StackLayout : LayoutEngine
        {
            public override bool Layout(object container, LayoutEventArgs layoutEventArgs)
            {
                if (container is not Control parent)
                    return false;

                var bounds = parent.ClientRectangle;
                bounds.Offset(parent.Padding.Left, parent.Padding.Top);
                bounds.Inflate(-parent.Padding.Left - parent.Padding.Right, -parent.Padding.Top - parent.Padding.Bottom);

                var startPoint = bounds.Location;

                foreach (var c in parent.Controls.Cast<Control>().Reverse())
                {
                    if (!c.Visible)
                        continue;

                    startPoint.Offset(c.Margin.Left, c.Margin.Top);

                    c.Location = startPoint;

                    if (c.AutoSize)
                    {
                        c.Size = c.GetPreferredSize(bounds.Size);
                    }
                    else
                    {
                        c.Width = bounds.Width - c.Margin.Left - c.Margin.Right;
                    }

                    startPoint.X = bounds.X;
                    startPoint.Y += c.Height + c.Margin.Bottom;
                }

                return false;
            }
        }
    }