gl_displayed_char_width
slen += gl_displayed_char_width(gl, *pptr, slen);
int width = gl_displayed_char_width(gl, c, term_curpos);
int old_width = gl_displayed_char_width(gl, gl->line[buff_curpos],
slen += gl_displayed_char_width(gl, string[i], term_curpos + slen);
static int gl_displayed_char_width(GetLine *gl, char c, int term_curpos);