Comment utiliser une cible RichTextBox comme une cible Nlog dans une application WPF?

J'ai créé une cible Nlog personnalisée et je l'ai associée à une zone de texte.

public class NlogMemoryTarget : Target
{
    public Action<string> Log = delegate { };

    public NlogMemoryTarget (string name, LogLevel level)
    {
        LogManager.Configuration.AddTarget (name, this);

        LogManager.Configuration.LoggingRules.Add(new LoggingRule("*", level, this));//This will ensure that exsiting rules are not overwritten
        LogManager.Configuration.Reload(); //This is important statement to reload all applied settings

        //SimpleConfigurator.ConfigureForTargetLogging (this, level); //use this if you are intending to use only NlogMemoryTarget  rule
    }

    protected override void Write (AsyncLogEventInfo[] logEvents)
    {
        foreach (var logEvent in logEvents) {
            Write (logEvent);
        }
    }

    protected override void Write (AsyncLogEventInfo logEvent)
    {
        Write (logEvent.LogEvent);
    }

    protected override void Write (LogEventInfo logEvent)
    {
        Log (logEvent.FormattedMessage);
    }
}


public partial class MainWindow
{
    private NlogMemoryTarget _Target;

    public MainWindow ()
    {
        InitializeComponent ();

        this.Loaded += (s, e) => {
            _Target = new NlogMemoryTarget ("text box output", LogLevel.Trace);
            _Target.Log += log => LogText (log);
        };
    }

    private void LogText (string message)
    {
        this.Dispatcher.Invoke ((Action) delegate () {
            this.MessageView.AppendText (message + "\n");
            this.MessageView.ScrollToEnd ();
        });
    }
}