#default_value doesn't work with SELECT OPTGROUPs

G'day,

I have noticed that the '#default_value' property doesn't seem to work as expected with form elements of '#type'=>'select' when the '#options' property contains a nested array for the output of option groups - <OPTGROUP/>.

In the following code the '#default_value' does not work as expected:

  $day_in_seconds = 60*60*24; 
  // Calculate dates for timeframes.
  $option_today = date('d-m-Y');
  $option_today1 = date('d-m-Y', strtotime('+1 day'));
  $option_today2 = date('d-m-Y', strtotime('+2 day'));
  $option_today6 = date('d-m-Y', strtotime('+6 day'));
  $option_weekend_begins = date('d-m-Y', (strtotime('sunday') - (2 * $day_in_seconds) < strtotime('today') ? strtotime('today') : strtotime('sunday') - 2 * $day_in_seconds));
  $option_weekend_ends = date('d-m-Y',strtotime('sunday'));
  
  // Set option values corresponding to their labels.
  $options_times = array(
    'single' => array(
      $option_today . ',' . $option_today        => t('Today'),
      $option_today1 . ',' . $option_today1       => t('Tomorrow'),
    ),
    'multiple' => array(
      $option_today . ','                        => t('From today'),
      $option_today . ',' . $option_today2       => t('Next three days'),
      $option_today . ',' . $option_today6       => t('Next seven days'),
      $option_weekend_begins . ',' . $option_weekend_ends => t('This weekend'),
    ),
    t('My dates (from, to)'),
  );
  
  $form['daterange'] = array(
    '#type' => 'select',
    '#title' => t('Select date range'),
    '#options' => $options_times,
    '#default_value' => array_search(t('Next seven days'), $options_times),
    '#prefix' => '<div id="edit-daterange-container">',
    '#suffix' => '</div>',
    '#required' => FALSE,
  );

Whereas, if I remove the nesting from the '#options' property array, and thereby removing the option groupings - <OPTGROUP/>s - the '#default_value' property works as you might expect:

  $day_in_seconds = 60*60*24; 
  // Calculate dates for timeframes.
  $option_today = date('d-m-Y');
  $option_today1 = date('d-m-Y', strtotime('+1 day'));
  $option_today2 = date('d-m-Y', strtotime('+2 day'));
  $option_today6 = date('d-m-Y', strtotime('+6 day'));
  $option_weekend_begins = date('d-m-Y', (strtotime('sunday') - (2 * $day_in_seconds) < strtotime('today') ? strtotime('today') : strtotime('sunday') - 2 * $day_in_seconds));
  $option_weekend_ends = date('d-m-Y',strtotime('sunday'));
  
  // Set option values corresponding to their labels.
  $options_times = array(
//    'single' => array(
      $option_today . ',' . $option_today        => t('Today'),
      $option_today1 . ',' . $option_today1       => t('Tomorrow'),
//    ),
//    'multiple' => array(
      $option_today . ','                        => t('From today'),
      $option_today . ',' . $option_today2       => t('Next three days'),
      $option_today . ',' . $option_today6       => t('Next seven days'),
      $option_weekend_begins . ',' . $option_weekend_ends => t('This weekend'),
//    ),
    t('My dates (from, to)'),
  );
  
  $form['daterange'] = array(
    '#type' => 'select',
    '#title' => t('Select date range'),
    '#options' => $options_times,
    '#default_value' => array_search(t('Next seven days'), $options_times),
    '#prefix' => '<div id="edit-daterange-container">',
    '#suffix' => '</div>',
    '#required' => FALSE,
  );

If I'm mistaken and this is not a bug, but a problem with my usage of '#default_value' for form elements of '#type'=>'select', please let me know where I'm going wrong.

Thanks for your consideration and/or help,
Christopher
(ourbrisbane.com)