title: MahApps Context is not registered on startup
body: <p>I have WPF MVVM app with the MahApps Shell Window which loads couple of Pages. On the ShellWindow I have setup the <code>DialogParticipation.Register</code> which I inject to Page ViewModels. So far this approach works when the code executes via commands. However, in one of the Pages I have to load data from external API in the constructor. When request errors I am showing the mahapps <code> await _dialogCoordinator.ShowMessageAsync(this, &quot;Error&quot;, ex.Message, MessageDialogStyle.Affirmative);</code> This is where the well known error appears <code>Context is not registered. Consider using DialogParticipation.Register in XAML </code>. it feels like it is a timing issue within constructor initialiazation but I am not sure how to deal with it properly.</p>
  <pre><code>&lt;mah:MetroWindow x:Class=&quot;ShellWindow&quot;
                  bla bla
                   xmlns:Dialog=&quot;clr-namespace:MahApps.Metro.Controls.Dialogs;assembly=MahApps.Metro&quot;
                   Dialog:DialogParticipation.Register=&quot;{Binding}&quot;
                   mc:Ignorable=&quot;d&quot;&gt;
  
   public ShellWindow(bool isData)
          {
             
              Main.Content = new PageOne(DialogCoordinator.Instance, this);
          }
  </code></pre>
  <p>Page One</p>
  <pre><code>public PageOne(IDialogCoordinator dialogCoordinator, ShellWindow shellWindow)
  {
      InitializeComponent();
  
      _dialogCoordinator = dialogCoordinator;
      _shellWindow = shellWindow;
      DataContext = this;
     
      new Action(async () =&gt; await LoadReports())();
  }
      
  private async Task LoadReports()
  {
      try {
          // API Request
      }
      catch (Exception ex)
      {
         // This is where the error happens
           _ = await _dialogCoordinator.ShowMessageAsync(this, &quot;Error&quot;, ex.Message, MessageDialogStyle.Affirmative);
      }
  }
  </code></pre>