Контейнеры: распределение места и прокрутка

using Reckfell;

public partial class ContainersDemo : Control
{
    public HBoxContainer Row { get; private set; } = null!;
    public PanelContainer A { get; private set; } = null!;
    public PanelContainer B { get; private set; } = null!;
    public PanelContainer C { get; private set; } = null!;
    public ScrollContainer Scroll { get; private set; } = null!;
    public Button Last { get; private set; } = null!;

    public override void _Ready()
    {
        UiSampleStyle.Prepare(this);
        var margin = new MarginContainer(); AddChild(margin);
        margin.SetAnchorsAndOffsetsPreset(LayoutPreset.FullRect, margin: 16);
        var column = new VBoxContainer(); margin.AddChild(column);
        column.AddChild(new Label { Text = UiSampleStyle.Text("Контейнеры и прокрутка", "Containers and scrolling") });
        Row = new HBoxContainer(); column.AddChild(Row);
        A = Item("A", 64); B = Item("B", 64); C = Item("C", 64);
        A.CustomMaximumSize = new Vector2(140, -1);
        A.SizeFlagsHorizontal = SizeFlags.ExpandFill; B.SizeFlagsHorizontal = SizeFlags.ExpandFill;
        B.SizeFlagsStretchRatio = 2; C.SizeFlagsHorizontal = SizeFlags.Fill;
        Row.AddChild(A); Row.AddChild(B); Row.AddChild(C);
        Scroll = new ScrollContainer
        {
            SizeFlagsVertical = SizeFlags.ExpandFill, FollowFocus = true,
            HorizontalScrollMode = ScrollContainer.ScrollMode.Disabled
        };
        column.AddChild(Scroll);
        var list = new VBoxContainer { SizeFlagsHorizontal = SizeFlags.ExpandFill }; Scroll.AddChild(list);
        for (int i = 1; i <= 20; i++)
        {
            Last = new Button { Text = UiSampleStyle.Text("Пункт ", "Item ") + i, CustomMinimumSize = new Vector2(0, 40) };
            list.AddChild(Last);
        }
    }

    private static PanelContainer Item(string text, float width)
    {
        var panel = new PanelContainer { CustomMinimumSize = new Vector2(width, 60) };
        panel.AddChild(new Label { Text = text, HorizontalAlignment = HorizontalAlignment.Center });
        return panel;
    }

    public void RevealLast()
    {
        Last.GrabFocus();
        Callable.From(() => Scroll.EnsureControlVisible(Last)).CallDeferred();
    }
}