SHS does not work in field collections, posible other side effects

Also validation function shs_field_widget_validate does not work correctly with field collections.

I suggest the following solution:

<?php
function shs_field_widget_validate($element, &$form_state, $form) {
  $field_name = $element['#field_name'];

  $instance = field_widget_instance($element, $form_state);

  if (empty($instance['widget'])) {
    return;
  }
  $field = field_widget_field($element, $form_state);
  $settings = empty($instance['widget']['settings']['shs']) ? array() : $instance['widget']['settings']['shs'];

  // Do we want to force the user to select terms from the deepest level?
  $force_deepest_level = empty($settings['force_deepest']) ? FALSE : $settings['force_deepest'];
  $value = empty($element['#value']) ? 0 : $element['#value'];
  if ($force_deepest_level && $value) {
    // Get vocabulary.
    $allowed_values = reset($field['settings']['allowed_values']);
    if (empty($allowed_values['vocabulary']) || ($vocabulary = taxonomy_vocabulary_machine_name_load($allowed_values['vocabulary'])) === FALSE) {
      // No vocabulary selected yet or vocabulary not found.
      form_error($element, t('Vocabulary %machine_name is configured as source for field %field_name but could not be found.', array('%machine_name' => $allowed_values['vocabulary'], '%field_name' => $field_name)));
    }
    // Does the selected term has any children?
    $children = shs_term_get_children($vocabulary->vid, $value);
    if (count($children)) {
      form_error($element, t('You need to select a term from the deepest level.'));
    }
  }
}
?>

What did not work in validation?

I'm using SHS within the module inline entity form, which is inside the field collections. In this case, the validation function shs_field_widget_validate does not work correctly. My code above solves this problem.

The patch is attached.

Wow, thanks for your patches.
I have committed the patch and some additional changes so Simple hierarchical select works in field collections and in inline entity forms.

Just a quick update to note that this was committed to the dev branch over a year ago, but has not made it to the stable branch yet. Dev branch seems to be working for me so far. Any idea when stable will be updated?