fill_utf8
int seqlen = fill_utf8(c, str);
outpos += fill_utf8((c), (char *)buffer + outpos); \
len += fill_utf8((code | modifiers) + 0x20, utf8 + len);
len += fill_utf8(col + 0x21, utf8 + len);
len += fill_utf8(row + 0x21, utf8 + len);