Implements hook_field_widget_form_alter().
function field_test_field_widget_form_alter(&$element, &$form_state, $context) {
switch ($context['field']['field_name']) {
case 'alter_test_text':
drupal_set_message('Field size: ' . $context['instance']['widget']['settings']['size']);
break;
case 'alter_test_options':
drupal_set_message('Widget type: ' . $context['instance']['widget']['type']);
break;
}
}