// Converts to u16string before adding.
        public void AddText(string text)
        {
            var            icu_text = icu.UnicodeString.fromUTF8(text);
            std::u16string u16_text = new std::u16string(icu_text.getBuffer(), icu_text.getBuffer() + icu_text.length());

            AddText(u16_text);
        }
 // Adds text to the builder. Forms the proper runs to use the upper-most style
 // on the style_stack_;
 public void AddText(std::u16string text)
 {
     text_.AddRange(text);
 }