Date Popup causing multiple problems

I've noticed two problems recently which I think relate to Date Popup:
1 - #601814: Incompatible with Multistep (disabling date_popup fixes problem)
2 - Changing textfields in webform to date_popup cause Views interface to mess up

Regarding the 2nd problem, I have a webform that is displayed in a block on all pages of my site. In a custom module, I've added some code to change two textfields in the webform to date_popups. This appears to be causing a problem in Views whereby the interface for editing a view is messed up (displays are not hidden but shown all at once). If I remove the two lines of code that convert the textfields to date_popups (problem lines as below), Views is fixed...

Here's the code I'm using:

<?php
/**
 * Implementation of hook_form_FORM_ID_alter().
 *
 * Add date popups to date fields
 * Add 'Advanced Search' link
 */
function brat_custom_form_webform_client_form_28_alter(&$form, &$form_state) {
  $form['submitted']['second_line']['depart']['#type'] = 'date_popup'; // Problem line 1
  $form['submitted']['second_line']['depart']['#date_format'] = 'd/m/Y';
  $form['submitted']['second_line']['arrive']['#type'] = 'date_popup'; // Problem line 2
  $form['submitted']['second_line']['arrive']['#date_format'] = 'd/m/Y';
  $form['submitted']['advanced']['#description'] = '<a href="#">Advanced Search</a>';
}
?>

Any idea why date_popup is seemingly causing these two problems?