title: Take necessary ViewModel from ChildVM and set it to property in ParentVM
body: <p>I have MainViewModel which looks like this </p>
  
  <pre><code>public class MainViewModel : ReactiveObject 
  {
      public MenuViewModel MenuVM { get;set; }
  
      [Reactive] IOverlayViewModel OverlayVM { get;set; } 
  }
  </code></pre>
  
  <p>So my problem is to make communication between MainViewModel and MenuViewModel. MenuViewModel responsible for MenuControl and should set necessary ViewModel to OverlayVM depeding on which button user clicked to display Overlay with choosed menu item. </p>
  
  <p>So how should i make this to work? Make event in MenuViewModel, subsctibe to it in MainViewModel and call it everytime when user click on menu item with viewmodel as argument? Help me to find the best way to solve this problem!</p>