title: Get IObservable from all Property Changed events on T.MyProperty in SortedList<MyClass>
body: <p>I have a Class, <code>MyClass</code> that implements <code>INotifyPropertyChanged</code> and has some properties that implement <code>PropertyChanged</code>.  When <code>MyClass.MyProperty</code> changes, <code>PropertyChanged</code> fires as expected.   Another class contains a <code>SortedList&lt;MyClass&gt;</code> .I've tried merging the events into a single observable in the class that contains the <code>SortedSet&lt;MyClass&gt;</code> and subscribing to it, but it doesn't seem to ever have any events.  Here's what I'm trying:</p>
  
  <pre><code>Observable.Merge(MySortedList.ToObservable())
     .Subscribe(evt =&gt; Console.WriteLine("{0} changed", evt.MyProperty));
  </code></pre>
  
  <p>What I'm trying to get is a single observable that contains all of the events from every item in my <code>SortedList&lt;MyClass&gt;</code>.  I've tried using ObservableCollection instead, but that doesn't change anything, nor would it be expected to, really, since it doesn't fire collectionchanged when a property of a contained item changes, anyway.  I can listen to individual elements in <code>SortedList&lt;MyClass&gt;</code> and see the PropertyChanged event fire, but what I want is a single Observable that contains a stream of ALL of the PropertyChanged events from all of the elements in <code>SortedList&lt;MyClass&gt;</code>.</p>
  
  <p>It seems like this should be something fairly easy to do using Rx, but I can't seem to figure out how.</p>