The event is signalled by the config plugin, lib/plugins/config/settings/config.class.php after it retrieves the plugin list from the plugin controller. It can be used to filter the plugins handled by this plugin.
An indexed array of plugin names.
NOTE: The plugin list includes all plugins installed, including any disabled plugins. There is no indication in the list whether or not the plugin is currently disabled. To discover whether or not a plugin is disabled use either:
plugin_isdisabled('plugin_name'); // inc/pluginutils.php
// or
global $plugin_controller;
$plugin_controller->isdisabled('plugin_name'); // inc/pluginutils.php (maybe overridden in preload.php)
The following plugins are known to handle this event and their source code may be a good start for understanding and implementing a handler yourself.

The event is designed to allow wiki farms to control visibility of plugins to administrators of the individual wikis that make up the farm.