Display posts order by custom post in a dropdown menu

Now I can order de post_types. Any help for the multiple save?

// The Callback  

function show_custom_meta_box_related() {
global $custom_meta_fields_related, $post;
// Use nonce for verification
echo ”;

// Begin the field table and loop  
echo '<table class="form-table">';  
foreach ($custom_meta_fields_related as $field_related) {  
    // get value of this field if it exists for this post  
    $meta_related = get_post_meta($post->ID, $field_related['id'], true);  
    // begin a table row with  
    echo '<tr> 
            <th><label for="'.$field_related['id'].'">'.$field_related['label'].'</label></th> 
            <td>';  
            switch($field_related['type']) {  
                // case items will go here 

                // post_list  
                case 'post_list': 
                echo '<select multiple style="height:200px; width:300px" name="'.$field_related['id'].'" id="'.$field_related['id'].'">';
                echo '<option value=""></option>'; // Select One
                foreach($field_related['post_type'] as $tipo_post){
                $items = get_posts( array (  
                    'post_type' => $tipo_post,  
                    'posts_per_page' => -1  
                )); 

                foreach($items as $item) {  
                    echo '<option value="'.$item->ID.'"',$meta_related == $item->ID ? ' selected="selected"' : '','> '.$item->post_title. '</option>';  
                } // end foreach

                }
                echo '</select><br /><span class="description">'.$field_related['desc'].'</span>';  
                break;
            } //end switch  
    echo '</td></tr>';  
} // end foreach  
echo '</table>'; // end table  

}