$form = array();
  $form['title'] = array(
    '#type' => 'textfield',
    '#title' => t('Space name'),
    '#attributes' => array('class' => 'dw-form-item'),
    '#required' => TRUE,
    '#description' => t('Enter the name of the space.'),
    '#weight' => -19,
  );
  $form['descr'] = array(
    '#type' => 'item',
    '#tree' => TRUE,
  );
  $form['descr']['body'] = array(
    '#type' => 'textarea',
    //'#maxlength' => ...,
    '#title' => t('Space description'),
    '#description' => t('That content will be shown to all users when entering the space'),
    '#default_value' => '',
    '#rows' => 10,
  );

  //filter_form();
  $form['descr']['filter'] = filter_form();