Unicode question

[Gonzalo Garramuño]

Since Matt is our C++ expert and Albretch is our Unicode one.  Is there
a way in FLTK to replace with an FLTK function this outdated code:

#if defined(_WINDOWS)
            //! \bug
            //!
https://social.msdn.microsoft.com/Forums/vstudio/en-US/8f40dcd8-c67f-4eba-9134-a19b9178e481/vs-2015-rc-linker-stdcodecvt-error?forum=vcgeneral
            typedef unsigned int tl_char_t;
#else  // _WINDOWS
            typedef char32_t tl_char_t;
#endif // _WINDOWS

std::wstring_convert<std::codecvt_utf8<tl_char_t>, tl_char_t>
                utf32Convert;