title: WPF RichTextBox text from bottom
body: <p>I'm trying to make a chat window, like IRC, in which the contents are shown from bottom to top, just like any chat window ever created.</p>
  
  <p>This is my xaml, nothing fancy about it</p>
  
  <pre><code>&lt;Window
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:ee="http://schemas.microsoft.com/expression/2010/effects" xmlns:ed="http://schemas.microsoft.com/expression/2010/drawing" x:Class="TestChat.Chat"
      Title="Chat" Height="700" Width="400" WindowStyle="ThreeDBorderWindow" ResizeMode="CanMinimize"&gt;
  
      &lt;Grid&gt;
          &lt;RichTextBox x:Name="txtChat" HorizontalAlignment="Left" Height="644" Margin="0,10,0,0" VerticalAlignment="Top" Width="388" VerticalScrollBarVisibility="Auto"&gt;
              &lt;FlowDocument /&gt;
          &lt;/RichTextBox&gt;
      &lt;/Grid&gt;
  &lt;/Window&gt;
  </code></pre>
  
  <p>And i have a backgroundworker adding text to it</p>
  
  <pre><code>private void SendWorkerComplete(object s, ProgressChangedEventArgs args)
  {
      txtChat.AppendText(args.UserState.ToString());
      txtChat.ScrollToEnd();
  }
  
  private void SendWorker_DoWork(object sender, DoWorkEventArgs e)
  {
      SendWorker.ReportProgress(0, (string)e.Argument);
  }
  </code></pre>
  
  <p>The VerticalContentAlignment property set to bottom does not render the contents this way, how could this be done? is there a property for it or it has to be done programmatically?</p>