automactic & smart loader for each column. Example with twig_bm_categories extending bm_categorie class and its template file

base.html.twig

{% block columnleft %}
    <div id="columnTwigLeft" class="span{{ GridColumnWidth }}">
        {% for boxe in boxes %}
              {% if boxe.boxe != null and boxe.group == 'boxes_column_left' %}
              {% include [boxe.boxe, TwigExtension]|join with{'data': boxe.data, 'title' : boxe.title } %}
              {% endif %}
        {% endfor %}
    </div>
{% endblock %}

{% block appcontent %}

{% endblock %}

{% block columnright %}
    <div id="columnTwigRight" class="span{{ GridColumnWidth }}">
        {% for boxe in boxes %}
              {% if boxe.boxe != null and boxe.group == 'boxes_column_right' %}              
              {% include [boxe.boxe, TwigExtension]|join with{'data': boxe.data, 'title' : boxe.title } %}
              {% endif %}
        {% endfor %}
    </div>
{% endblock %}

twig_bm_categories.html.twig

{# Copyright (c) 2013 FoxP2; http://www.oscommerce.fr #}
{# file: includes/modules/boxes/view/template/classic/twig_bm_categories.html.twig #}
<div class="media well">
    <span class="pull-left">
        <i class="icon-list icon-large text-info"></i>
    </span>
    <div class="media-body">        
    <h4 class="media-heading text-info">{{ title }}</h4>
      <ul class="nav nav-list">
          {{ data | raw }}
      </ul>
    </div>
</div>

twig_bm_categories.php

<?php
/**
 * osCommerce Online Merchant
 *
 * @copyright Copyright (c) 2013 osCommerce; http://www.oscommerce.com
 * @copyright Copyright (c) 2013 FoxP2; http://www.oscommerce.fr
 * @license GNU General Public License; http://www.oscommerce.com/gpllicense.txt
 */

require(DIR_WS_MODULES . 'boxes/bm_categories.php');

  class twig_bm_categories extends bm_categories {
    var $code = 'twig_bm_categories';
    
    public function __construct() {
        parent::bm_categories();
    }

    public function execute() { 
      global $cPath;
      
      $OSCOM_CategoryTree = new category_tree();    
      
      $OSCOM_CategoryTree->setCategoryPath($cPath, '<strong>','</strong>');
      $OSCOM_CategoryTree->setRootString('<i class="icon-chevron-right pull-left text-info" style="padding-top:5px;"></i>','');      
      $OSCOM_CategoryTree->setParentGroupString('<ul class="nav nav-list">', '</ul>');

      $data = array('data' => $OSCOM_CategoryTree->getTree(),
          'group' => $this->group,
          'boxe' => $this->code,
          'enabled' => $this->enabled,
          'sort_order' => $this->sort_order,
          'title' => $this->title);

      return $data;
    }
  }
?>