spower.module

<?php

function spower_menu() {
  $items = array();
  $items['spower'] = array(
    'title' => t('My form'),
    'page callback' => 'spower_form',
    'access arguments' => array('access content'),
    'description' => t('My form'),
    'type' => MENU_CALLBACK,
  );
  return $items;
}

function spower_form() {
  return drupal_get_form('spower_my_form');
}

function spower_my_form($form, &$form_state, $no_js_use = FALSE) {
  $form['name'] = array(
    '#type' => 'fieldset',
    '#title' => t('Name'),
    '#collapsible' => FALSE,
    '#collapsed' => FALSE,
  );

   $form['#tree'] = TRUE;
   $form['names_fieldset'] = array(
    '#type' => 'fieldset',
    '#title' => t('People coming to the picnic'),
    // Set up the wrapper so that AJAX will be able to replace the fieldset.
    '#prefix' => '<div id="names-fieldset-wrapper">',
    '#suffix' => '</div>',
  );

  $form['name']['first'] = array(
    '#type' => 'textfield',
    '#title' => t('First name'),
    '#required' => TRUE,
    '#default_value' => "First name",
    '#description' => "Please enter your first name.",
    '#size' => 20,
    '#maxlength' => 20,
  );
  $form['name']['last'] = array(
    '#type' => 'textfield',
    '#title' => t('Last name'),
    '#required' => TRUE,
  );
  $form['name']['year_of_birth'] = array(
    '#type' => 'textfield',
    '#title' => "Year of birth",
    '#description' => 'Format is "YYYY"',
  );


  // Build the fieldset with the proper number of names. We'll use
  // $form_state['num_names'] to determine the number of textfields to build.
  if (empty($form_state['num_names'])) {
    $form_state['num_names'] = 1;
  }
  for ($i = 0; $i < $form_state['num_names']; $i++) {
    $form['names_fieldset']['name'][$i] = array(
      '#type' => 'textfield',
      '#title' => t('Name'),
    );
  }
  $form['names_fieldset']['add_name'] = array(
    '#type' => 'submit',
    '#value' => t('Add one more'),
    '#submit' => array('spower_add_more_add_one'),
    // See the examples in ajax_example.module for more details on the
    // properties of #ajax.
    '#ajax' => array(
      'callback' => 'spower_add_more_callback',
      'wrapper' => 'names-fieldset-wrapper',
    ),
  );
  if ($form_state['num_names'] > 1) {
    $form['names_fieldset']['remove_name'] = array(
      '#type' => 'submit',
      '#value' => t('Remove one'),
      '#submit' => array('spower_add_more_remove_one'),
      '#ajax' => array(
        'callback' => 'spower_add_more_callback',
        'wrapper' => 'names-fieldset-wrapper',
      ),
    );
  }


  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => 'Submit',
    '#ajax' => array(
              'callback' => 'spower_ajax_callback',
              'wrapper' => 'tabs-3',
          ),

  );
  return $form;
}

function spower_theme($existing, $type, $theme, $path) {
  $base = array(
    'render element' => 'form',
  );

  return array(
    'spower_my_form' => $base + array(
      'template' => 'spower',
    ),
  );
}

function spower_my_form_validate($form, &$form_state) {
    $year_of_birth = $form_state['values']['year_of_birth'];
    if ($year_of_birth && ($year_of_birth < 1900 || $year_of_birth > 2000)) {
        form_set_error('year_of_birth', 'Enter a year between 1900 and 2000.');
    }
}

// Adds a submit handler/function to our form to send a successful
// completion message to the screen.


function spower_my_form_submit($form, &$form_state) {
    drupal_set_message(t('The form has been submitted.'));
};

function spower_ajax_callback($form, $form_state){
    return "<div id=\"tabs-3\">hello world</div>";

}

function spower_add_more_callback($form, $form_state) {
  return $form['names_fieldset'];
}

/**
 * Submit handler for the "add-one-more" button.
 *
 * Increments the max counter and causes a rebuild.
 */
function spower_add_more_add_one($form, &$form_state) {
  $form_state['num_names']++;
  $form_state['rebuild'] = TRUE;
}

/**
 * Submit handler for the "remove one" button.
 *
 * Decrements the max counter and causes a form rebuild.
 */
function spower_add_more_remove_one($form, &$form_state) {
  if ($form_state['num_names'] > 1) {
    $form_state['num_names']--;
  }
  $form_state['rebuild'] = TRUE;
}

?>