WPF

private void SaveToXps(string fileName, RichTextBox rtb)
{
  if (string.IsNullOrEmpty(fileName))
  {
    throw new ArgumentNullException("fileName");
  }
  // If the file doesn't end in .xps, add the extension
  if (Path.GetExtension(fileName).ToLower() != ".xps")
  {
    fileName += ".xps";
  }

  using (FileStream stream = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite))
  {
    TextRange range = new TextRange(rtb.Document.ContentStart, rtb.Document.ContentEnd);
    range.Save(fileName, DataFormats.XamlPackage);
  }
}

private void SaveToXps(string fileName)
      {
          if (string.IsNullOrEmpty(fileName))
          {
              throw new ArgumentNullException("fileName");
          }
          // If the file doesn't end in .xps, add the extension
          if (System.IO.Path.GetExtension(fileName).ToLower() != ".xps")
          {
              fileName += ".xps";
          }

          using (FileStream stream = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite))
          {
              TextRange range = new TextRange(FlowDocRdr.Document.ContentStart, FlowDocRdr.Document.ContentEnd);
              range.Save(stream, DataFormats.XamlPackage);
          }
      }

private void SaveToXps_1(object sender, RoutedEventArgs e)
        {
            SaveToXps("C:\\test1.xaml");
        }

<Window x:Class="WPFTester.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="150" Width="300" Background="SteelBlue" Loaded="Window_Loaded"  >
    <StackPanel>
        <TextBox Name="TextBox1" Margin="8" />
        <TextBox Name="TextBox2" Margin="8" />
        <Button Content="Test" Width="80"  Margin="8" Click="TestButton_Click"  />
    </StackPanel>
</Window>

namespace WPFTester
{
    public partial class Window1 : Window
    {
        Window2 window2;

        public Window1()
        {
            InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            window2 = new Window2();
            window2.Show();
        }

        private void TestButton_Click(object sender, RoutedEventArgs e)
        {
            window2.TextBox1.Text = this.TextBox1.Text;
            window2.TextBox2.Text = this.TextBox2.Text;
        }
    }
}

<Window x:Class="WPFTester.Window2"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window2" Height="116" Width="300" Background="SteelBlue" >
    <StackPanel>
        <TextBox Name="TextBox1" Margin="8" />
        <TextBox Name="TextBox2" Margin="8" />
    </StackPanel>
</Window>

namespace WPFTester
{
    public partial class Window2 : Window
    {
        public Window2()
        {
            InitializeComponent();
        }
    }
}

Mark Salsbery
Microsoft MVP - Visual C++