Custom language addition form.
function locale_languages_custom_form($form) {
$form['custom language'] = array(
'#type' => 'fieldset',
'#title' => t('Custom language'),
'#collapsible' => TRUE,
'#collapsed' => TRUE,
);
_locale_languages_common_controls($form['custom language']);
$form['custom language']['actions'] = array(
'#type' => 'actions',
);
$form['custom language']['actions']['submit'] = array(
'#type' => 'submit',
'#value' => t('Add custom language'),
);
// Reuse the validation and submit functions of the predefined language setup form.
$form['#submit'][] = 'locale_languages_predefined_form_submit';
$form['#validate'][] = 'locale_languages_predefined_form_validate';
return $form;
}