Hide WordPress plugins from the plugins.php admin screen in a flexible way

gistfile1.php

<?php

/**
 * Prevent specific plugins from being activated (or, in some cases, deactivated). 
 * 
 * Plugins that are to be deprecated should be added to the $disabled_plugins array.
 * 
 * Plugins that should be un-deactivatable should be added to the $undeactivatable_plugins array
 */
function cac_hide_plugins( $plugins ) {
	// Allow the super admin to see all plugins, by adding the URL param
	// show_all_plugins=1
	if ( is_super_admin() && ! empty( $_GET['show_all_plugins'] ) ) {
		return $plugins;
	}

	// The following plugins are disabled
	$disabled_plugins = array(
		'cforms/cforms.php',
		'wpng-calendar/wpng-calendar.php'
	);

	// By default, allow all disabled plugins to appear if they are
	// already active on the current site. This lets administrators
	// disable them. However, if you want a given plugin to be unlisted
	// even when enabled, add it to this array
	$undeactivatable_plugins = array(
		'cforms/cforms.php',
	);

	foreach ( $disabled_plugins as $disabled_plugin ) {
		if ( array_key_exists( $disabled_plugin, $plugins ) &&
		     ( in_array( $disabled_plugin, $undeactivatable_plugins ) || ! is_plugin_active( $disabled_plugin ) )
		) {
			unset( $plugins[ $disabled_plugin ] );
		}
	}

	return $plugins;
}
add_filter( 'all_plugins', 'cac_hide_plugins' );