如何在WPF应用程序中将RichTextBox用作NLog目标？

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

 <targets>
   <target xsi:type="RichTextBox" name="richTextBox" controlName="richTextBox" layout="${longdate} ${level:uppercase=true}: ${message} ${exception:format=ToString}" />
  </targets>

 <rules>
   <logger name="*" minlevel="Trace" writeTo="richTextBox" />
  </rules>
</nlog>

<RichTextBox x:Name="richTextBox" />

private static Logger logger = LogManager.GetCurrentClassLogger();

private void Button_Click(object sender, RoutedEventArgs e)
{
    logger.Info("Button clicked.");
}