title: Ajax progress bar using example module
body: <p>I am new to drupal, currently learning about example module and its sub module, I already created the form using custom modules, in that form I wish to add progress bar for submit button, i referred many sites but, i can't get any clear idea, what i did for submit button is,</p>
  
  <pre><code>function custom_form_menu() {
  $items = array();
  $items['think/form'] = array(
  'title' =&gt; t('Entry Free'),
  'page callback' =&gt; 'custom_form_form',
  'page arguments' =&gt; array('ajax_example_progressbar_form'),
  'access arguments' =&gt; array('access content'),
  'description' =&gt; t('My form'),
  'type' =&gt; MENU_CALLBACK,
  'file' =&gt; 'ajax_example_progressbar.inc',
  );
  return $items;
  }
  and for submit button,
  
  custom_form_my_form($form , &amp;$form_state) {
  $form['first'] = array(
  '#type' =&gt; 'textfield',
  '#title' =&gt; t('First name'),
  '#description' =&gt; "Please enter your first name.",
  '#maxlength' =&gt; 6,
  );
  $form['submit'] = array(
  '#type' =&gt; 'submit',
  '#value' =&gt; 'Submit',
  );
  return $form;
  }
  </code></pre>
  
  <p>So, now how can I add progress bar in this submit button, when the form is submitted.</p>