knpmenu + twitter bootstrap

builder.php

<?php

class Builder extends ContainerAware
{
    public function adminMenu(FactoryInterface $factory, array $options)
    {
        $menu = $factory->createItem('root');
        $menu->setChildrenAttribute('class', 'nav'); //esto es el tema
        $menu->setCurrentUri($this->container->get('request')->getRequestUri());
...

dropdown.twig

{% Con dropdown %}

{% extends "knp_menu.html.twig"  %}

{% block list %}
{% import "knp_menu.html.twig" as macros %}

{% set is_dropdown = listAttributes.dropdown|default(false) %}
{% set divider_prepend = listAttributes.divider_prepend|default(false) %}
{% set divider_append = listAttributes.divider_append|default(false) %}

{# unset bootstrap specific attributes #}
{% set listAttributes = listAttributes|merge({'dropdown': null, 'divider_prepend': null, 'divider_append': null }) %}

{% if item.hasChildren and options.depth is not sameas(0) and item.displayChildren %}
    {% if is_dropdown %}
        <ul{{ macros.attributes(listAttributes)}}>
            {% if divider_prepend %}
            <li class="divider-vertical"></li>
            {% endif %}
            <li class="dropdown">
                <a href="#" class="dropdown-toggle" data-toggle="dropdown">{{ item.label }} <b class="caret"></b></a>
                <ul class="dropdown-menu">
                    {{ block('children') }}
                </ul>
            </li>
            {% if divider_append %}
            <li class="divider-vertical"></li>
            {% endif %}
        </ul>
    {% else %}
        {{ parent() }}
    {% endif %}
{% endif %}
{% endblock %}