ustring byte index vs character index (API 2.4)

[Yann Leydier <yann leydier info>]

Hi,

I hope this is the right place to ask, I have a problem with 
Pangomm::GliphString::index_to_x(). One argument of the method is a byte 
index in a ustring, and I need to call the method on each character.

However there seems to be no way of knowning where characters begin in a 
ustring's byte field.

ustring::bytes() returns the number of bytes wheras ustring::size() 
returns the number of characters, but I found no way of stepping through 
characters using their byte index. Is there some kind of 
"next_character(size_t position)" method or is this a flaw in Pangomm 
integration ?

Thanks,
yann