public MonitoringInstancesViewModelFactory(IViewModelFactory innerViewModelFactory, TimeSpan time)
		{
			if (innerViewModelFactory == null) throw new ArgumentNullException("innerViewModelFactory");
			_innerViewModelFactory = innerViewModelFactory;

			_instanceMonitor = InstanceTracker.MonitorByType<IViewModel>(time);
			_instanceMonitor.Update += _instanceMonitor_Update;
		}
        public MonitoringInstancesViewModelFactory(IViewModelFactory innerViewModelFactory, TimeSpan time)
        {
            if (innerViewModelFactory == null)
            {
                throw new ArgumentNullException("innerViewModelFactory");
            }
            _innerViewModelFactory = innerViewModelFactory;

            _instanceMonitor         = InstanceTracker.MonitorByType <IViewModel>(time);
            _instanceMonitor.Update += _instanceMonitor_Update;
        }