Is that the wide-character version of ncurses? (libncursesw).
ncursesw provides get_wch(), which decoded the UTF-8. For instance, I
use the ncurses test-programs to check this area.
I linked my test-program against ncursesw. get_wch() just hangs and
does not return for a long time when I enter something cyrillic.
getchar() and getch() returns multiple values for each keypress, which I
decode to ensure that the encoding is UTF-8. Don't know whether this
information is relevant/useful since vile does not use get_wch().