mutt_error ("Threading is not enabled.");
mutt_error _("Threading is not enabled.");
int mutt_thread_set_flag (HEADER *cur, int flag, int bf, int subthread){  HEADER *start;    if ((Sort & SORT_MASK) != SORT_THREADS)  {    mutt_error ("Threading is not enabled.");    return (-1);  }  if (!subthread)    while (cur->parent)      cur = cur->parent;  start = cur;    mutt_set_flag (Context, cur, flag, bf);  if ((cur = cur->child) == NULL)    return (0);  FOREVER  {    mutt_set_flag (Context, cur, flag, bf);    if (cur->child)      cur = cur->child;    else if (cur->next)      cur = cur->next;    else     {      while (!cur->next)      {	cur = cur->parent;	if (cur == start)	  return (0);      }      cur = cur->next;    }  }  /* not reached */}