How to use TYPO3 hooks to customise what is displayed in a given listing.

customise.php

# 1. Make an empty extension

# 2. ext_tables.php

<?php

require_once t3lib_extMgm::extPath('dblist_hook') . '/class.user_tx_belisthook.php';
$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['typo3/class.db_list_extra.inc']['getTable'][] = 'user_tx_belisthook';

?>

# 3. class.user_tx_belisthook.php

<?php

class user_tx_belisthook implements t3lib_localRecordListGetTableHook
{
  public function getDBlistQuery($table, $pageId, &$additionalWhereClause, &$selectedFieldsList, &$parentObject)
  {
    $additionalWhereClause .= ' and 0 '; # << whatever you like here
  }
}

?>