How can I Save, Load, and Print RichTextBox Content ?

This can be done using the XAML code as given below.

[XAML]

<Page xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'
  xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
  x:Class='SDKSample.SaveLoadPrintRTB' >

  <StackPanel>
    <RichTextBox Name='richTB'>
      <FlowDocument>
        <Paragraph>
          <Run>Paragraph 1</Run>
        </Paragraph>
      </FlowDocument>
    </RichTextBox>

    <Button Click='SaveRTBContent'>Save RTB Content</Button>
    <Button Click='LoadRTBContent'>Load RTB Content</Button>
    <Button Click='PrintRTBContent'>Print RTB Content</Button>
  </StackPanel>
</Page>

Below is the code-behind for the example.

[C#]

// Handle 'Save RichTextBox Content' button click.
        void SaveRTBContent(Object sender, RoutedEventArgs args)
        {

            // Send an arbitrary URL and file name string specifying
            // the location to save the XAML in.
            SaveXamlPackage('C:\\test.xaml');
        }

        // Handle 'Load RichTextBox Content' button click.
        void LoadRTBContent(Object sender, RoutedEventArgs args)
        {
            // Send URL string specifying what file to retrieve XAML
            // from to load into the RichTextBox.
            LoadXamlPackage('C:\\test.xaml');
        }

        // Handle 'Print RichTextBox Content' button click.
        void PrintRTBContent(Object sender, RoutedEventArgs args)
        {
            PrintCommand();
        }

        // Save XAML in RichTextBox to a file specified by _fileName
        void SaveXamlPackage(string _fileName)
        {
            TextRange range;
            FileStream fStream;
            range = new TextRange(richTB.Document.ContentStart, richTB.Document.ContentEnd);
            fStream = new FileStream(_fileName, FileMode.Create);
            range.Save(fStream, DataFormats.XamlPackage);
            fStream.Close();
        }

        // Load XAML into RichTextBox from a file specified by _fileName
        void LoadXamlPackage(string _fileName)
        {
            TextRange range;
            FileStream fStream;
            if (File.Exists(_fileName))
            {
                range = new TextRange(richTB.Document.ContentStart, richTB.Document.ContentEnd);
                fStream = new FileStream(_fileName, FileMode.OpenOrCreate);
                range.Load(fStream, DataFormats.XamlPackage);
                fStream.Close();
            }
        }

        // Print RichTextBox content
        private void PrintCommand()
        {
            PrintDialog pd = new PrintDialog();
            if ((pd.ShowDialog() == true))
            {
                //use either one of the below      
                pd.PrintVisual(richTB as Visual, 'printing as visual');
                pd.PrintDocument((((IDocumentPaginatorSource)richTB.Document).DocumentPaginator), 'printing as paginator');
            }
      }