system_system_info_alter

system_system_info_alter(&$info, Extension $file, $type)

function system_system_info_alter(&$info, Extension $file, $type) {
  // Remove page-top and page-bottom from the blocks UI since they are reserved for
  // modules to populate from outside the blocks system.
  if ($type == 'theme') {
    $info['regions_hidden'][] = 'page_top';
    $info['regions_hidden'][] = 'page_bottom';
  }
}