ReactiveList monitoring

gistfile1.cs

        IObservable<bool> WhenAnyAreTrue(IEnumerable<SelItem> currentItems)
        {

            return currentItems != null && currentItems.Any()
                ? Observable.Return(currentItems.Any(p => p.Selected) != null)
                : Observable.Return(false);
        }
        
        
        // monitor changes of MySelectItems, elements, and collection
        
        this.WhenAnyValue(x => x.MySelectedItems).Select(_ => Unit.Default)
                .Select(x => 
                     Observable.Merge(MySelectedItems != null ? MySelectedItems.ItemChanged.Select(_ => Unit.Default) : Observable.Return(Unit.Default),
                                      MySelectedItems != null ? MySelectedItems.Changed.Select(_ => Unit.Default)     : Observable.Return(Unit.Default)))
                .Switch()
                .Select(_ => WhenAnyAreTrue(MySelectedItems))
                .Switch()
                .ToProperty(this,x => x.Selected,out _Selected,false);