acf-field-groups-settings-metabox.php

<?php
add_action('acf/field_group/admin_head', 'hwk_acf_field_groups_add_metabox');
function hwk_acf_field_groups_add_metabox(){
    add_meta_box('acf-field-group-options-plus', __('Options supplémentaires', 'acf'), function(){
        global $field_group;
        if(!acf_is_field_group_key( $field_group['key']))
            $field_group['key'] = uniqid('group_');
        
        $group = $field_group;

        acf_render_field_wrap(array(
            'label'         => __('Texte','acf'),
            'instructions'  => __('Instructions','acf'),
            'type'          => 'text',
            'name'          => 'hwk_text',
            'prefix'        => 'acf_field_group',
            'value'         => (isset($group['hwk_text'])) ? $group['hwk_text'] : '',
            'placeholder'   => 'placeholder',
            'prepend'       => 'prefixe',
            'append'        => 'suffixe',
            'maxlength'     => 2
        ));

        // ...

        ?>
        <script type="text/javascript">
        if(typeof acf !== 'undefined'){
            acf.postbox.render({
                'id':       'acf-field-group-options-plus',
                'label':    'left'
            });	
        }
        </script>
        <?php

    }, 'acf-field-group', 'normal', 'high');
}