public class Layer : BaseObject
{
    private ObservableCollection<LineShape> _shapes;

    public ObservableCollection<LineShape> Shapes
    {
        get { return _shapes; }
        set { Update(ref _shapes, value); }
    }

    public Layer(object owner = null, string name = null)
    {
        this.Owner = owner;
        this.Name = name;
        this.Shapes = new ObservableCollection<LineShape>();
    }
}

public class LayerViewModel : IDisposable
{
    private CompositeDisposable Disposable { get; set; }
    public ReactiveProperty<string> Name { get; set; }
    public ReadOnlyReactiveCollection<LineShapeViewModel> Shapes { get; set; }
    public ReactiveCommand UndoCommand { get; set; }
    public ReactiveCommand RedoCommand { get; set; }
    public ReactiveCommand ClearCommand { get; set; }

    public LayerViewModel(Layer layer, IHistory history)
    {
        Disposable = new CompositeDisposable();

        this.Name = layer.ToReactivePropertyAsSynchronized(l => l.Name)
            .SetValidateNotifyError(name => string.IsNullOrWhiteSpace(name) ? "Name can not be null or whitespace." : null)
            .AddTo(this.Disposable);

        this.Shapes = layer.Shapes
            .ToReadOnlyReactiveCollection(x => new LineShapeViewModel(x, history))
            .AddTo(this.Disposable);

        this.Name.ObserveWithHistory(name => layer.Name = name, layer.Name, history).AddTo(this.Disposable);
        
        UndoCommand = new ReactiveCommand(history.CanUndo, false);
        UndoCommand.Subscribe(_ => history.Undo()).AddTo(this.Disposable);

        RedoCommand = new ReactiveCommand(history.CanRedo, false);
        RedoCommand.Subscribe(_ => history.Redo()).AddTo(this.Disposable);

        ClearCommand = new ReactiveCommand(history.CanClear, false);
        ClearCommand.Subscribe(_ => history.Clear()).AddTo(this.Disposable);
    }

    public void Dispose()
    {
        this.Disposable.Dispose();
    }
}

var layer1 = new Layer("layer1");

var line1 = new LineShape(layer1, "line1");
line1.Start = new PointShape(100, 100, line1, "start11");
line1.End = new PointShape(200, 100, line1, "end11");

var line2 = new LineShape(layer1, "line2");
line2.Start = new PointShape(100, 200, line2, "start21");
line2.End = new PointShape(200, 200, line2, "end21");

layer1.Shapes.Add(line1);
layer1.Shapes.Add(line2);

var history = new StackHistory();
var layerViewModel = new LayerViewModel(layer1, history).AddTo(disposable);