title: Contentcontrol unable to update when content property changed from call within the loaded usercontrol
body: <p>I have a MainView that holds a single ContentControl, the ContentControl loads up a default usercontrol when the application loads.</p>
  
  <pre><code>&lt;ContentControl x:Name="MainContentArea" Content="{Binding ActiveControl}"/&gt;
  </code></pre>
  
  <p>The usercontrol that is loaded, loads a few plugins (irrelevant) and upon selecting an item from a combobox, it triggers a ICommand that exists in the Parent(MainViewModel) using MVVM Light´s concept of ViewModelLocator.</p>
  
  <pre><code>private void CreateSelectedPlugin(IExtendedUIViewFactory plugin)
      {
          var pluginStartControl = plugin.Create();
          _locator.Main.DefaultCommand.Execute(pluginStartControl);
      }
  </code></pre>
  
  <p>The problem is that the ContentControl is not updated, i can set a breakpoint and see that the command is executed in the MainViewModel and that the variable i send is valid.</p>
  
  <pre><code>public ICommand DefaultCommand { get; set; }
      public MainWindowViewModel()
      {
          DefaultCommand = new RelayCommand&lt;object&gt;(LoadSection, o =&gt; true);
      }
  
      private void LoadSection(object plugin)
      {
          ActiveControl = plugin;
          //does not matter if i set it to null here
      }
  </code></pre>
  
  <p>Calling the LoadSection or testfunction which just sets the ContentControl to null, from the MainView/MainViewModel, it works as expected.</p>
  
  <p>What hold does the command i send from within the control have on the Contentcontrol that makes it not want to load something else?</p>