wabbajack/Wabbajack.App/ViewModels/ViewModelBase.cs

using ReactiveUI;
using ReactiveUI.Validation.Helpers;

namespace Wabbajack.App.ViewModels
{
    public class ViewModelBase : ReactiveValidationObject, IActivatableViewModel
    {
        public ViewModelActivator Activator { get; protected set; }
    }
}