Is there a way to limit the options of the timezone field in the datetime or datetime range widget in Drupal 8? It currently shows tons of timezones, but we really only need about 10 options. I checked the default widget but did not see anything about how it was building that part of the widget form.
The core DateTime element appears to do:
$element['timezone'] = [ '#type' => 'select', '#options' => system_time_zones(FALSE, TRUE), // Default to user's time zone. '#default_value' => $element['#date_timezone'], '#required' => $element['#required'], ];
I guess the only way is to alter this element and configure the timezones that should be selectable?