tx.cs

public static bool ApplyMasterTemplate(this TextControl textControl,
  string masterTemplate, StreamType streamType)
{
    // list to keep all style names
    List<ParStyle> styles = new List<ParStyle>();

    using (ServerTextControl serverTextControl =
      new ServerTextControl())
    {
        serverTextControl.Create();

        // load the master template
        try {
            serverTextControl.Load(masterTemplate, streamType);
        }
        catch {
            return false;
        }

        // loop through all paragraphs to store the used
        // style names
        foreach (IFormattedText textPart in textControl.TextParts)
        {
            foreach (Paragraph par in textPart.Paragraphs)
            {
                ParStyle style = new ParStyle(par, par.FormattingStyle);
                styles.Add(style);
            }
        }

        // loop through all paragraph styles and
        // replace the style, if the name already exist
        foreach (ParagraphStyle style in serverTextControl.ParagraphStyles)
        {
            if (textControl.ParagraphStyles.GetItem(style.Name) != null)
            {
                textControl.ParagraphStyles.Remove(style.Name);

                // create a new style and add it to TextControl
                ParagraphStyle newStyle = new ParagraphStyle(style);
                textControl.ParagraphStyles.Add(newStyle);
            }
        }
    }

    // apply the stored style names to all paragraphs
    foreach (ParStyle par in styles)
    {
        par.Paragraph.FormattingStyle = par.StyleName;
    }

    return true;
}