title: Trying to understand Caliburn Micro EventAggregator
body: <p>I understood how does EventAggregator work in Caliburn Micro but i don't understand this:</p>
  
  <p>Let's take this as an example:</p>
  
  <p>ViewModel A</p>
  
  <pre><code>private IEventAggregator _eventAggregator;
  public ViewModelA(IEventAggregator eventAggregator)
  {
     _eventAggregator = eventAggregator
     _eventAggregator.PublishOnUIThread("Hello");
  }
  </code></pre>
  
  <p>ViewModel B</p>
  
  <pre><code>private IEventAggregator _eventAggregator;
  public ViewModelA(IEventAggregator eventAggregator)
  {
     _eventAggregator = eventAggregator
     _eventAggregator.Subscribe(this)
  }
  public void Handle(string message)
  { 
     MessageBox.Show(message + " From ViewModel B")
  }
  </code></pre>
  
  <p>ViewModel C</p>
  
  <pre><code>private IEventAggregator _eventAggregator;
  public ViewModelA(IEventAggregator eventAggregator)
  {
     _eventAggregator = eventAggregator
     _eventAggregator.Subscribe(this)
  }
  public void Handle(string message)
  { 
     MessageBox.Show(message + " From ViewModel C")
  }
  </code></pre>
  
  <p>So how can i select which viewmodel handle to use when i publish events?</p>