source: extensions/Front2Back/maintain.inc.php

<?php
if (!defined('PHPWG_ROOT_PATH')) die('Hacking attempt!');

function plugin_install()
{
  global $conf;

  if (!isset($conf['Front2Back'])) {
    $q = 'INSERT INTO ' . CONFIG_TABLE . ' (param,value,comment)
      VALUES ("Front2Back", ",thumbnail/verso/,pwg_high/verso/,", "Parametres Front2Back");';
    pwg_query($q);
  }
}

function plugin_activate()
{
  global $conf;

  if (!isset($conf['Front2Back'])) {
    $q = 'INSERT INTO ' . CONFIG_TABLE . ' (param,value,comment)
      VALUES ("Front2Back", ",thumbnail/verso/,pwg_high/verso/,", "Parametres Front2Back");';
    pwg_query($q);
  } else {
    $conf['Front2Back'] = explode(',', $conf['Front2Back']);
    if (!isset($conf['Front2Back'][4])) {
      $conf['Front2Back'][4] = 'top';
      $conf['Front2Back'][5] = 'click';
      $conf['Front2Back'][6] = 'none';
      $conf['Front2Back'][7] = serialize(array('default'=>null));
      conf_update_param('Front2Back', implode (',', $conf['Front2Back'])); 
    }
  }
}

function plugin_uninstall()
{
  global $conf;

  if (isset($conf['Front2Back'])) {
    pwg_query('DELETE FROM ' . CONFIG_TABLE . ' WHERE param="Front2Back";');
  }
}

?>