Mine

static int
ewl_callback_insert(Ewl_Widget *w, Ewl_Callback_Type t,
                                Ewl_Callback *cb, unsigned int pos)
{
        Ewl_Callback *old = NULL;

        DENTER_FUNCTION(DLEVEL_STABLE);
        DCHECK_PARAM_PTR_RET("w", w, 0);

        /* set direct if possible */
        if (!EWL_CALLBACK_LEN(w, t))
        {
                w->callbacks[t].list = (void *)cb;
                w->callbacks[t].len = 1;
                EWL_CALLBACK_SET_DIRECT(w, t);

                DRETURN_INT(cb->id, DLEVEL_STABLE);
        }
        w->callbacks[t].len ++;

        if (w->callbacks[t].mask & EWL_CALLBACK_TYPE_DIRECT)
        {
                old = (Ewl_Callback *)w->callbacks[t].list;
                w->callbacks[t].list = NULL;
                EWL_CALLBACK_SET_NODIRECT(w, t);
        }

        w->callbacks[t].list = realloc(w->callbacks[t].list,
                                    w->callbacks[t].len * sizeof(void *));

        /* if old is set this was a direct so we can just set 0,1 and be
         * done with it */
        if (old)
        {
                w->callbacks[t].list[0] = old;
                w->callbacks[t].list[1] = cb;
        }
        else
        {
                memmove(w->callbacks[t].list + ((pos + 1) * sizeof(void *)),
                        w->callbacks[t].list + (pos * sizeof(void *)),
                        w->callbacks[t].len);
                w->callbacks[t].list[pos] = cb;
        }

        DRETURN_INT(cb->id, DLEVEL_STABLE);
}