WordPress at a glance
action is not described

current_screen action-hook . WP 3.0.0

Fires after the current screen has been set.

Usage

add_action( 'current_screen', 'action_function_name_5398' );
function action_function_name_5398( $current_screen ){
	// action...
}
$current_screen(WP_Screen)
Current WP_Screen object.

Where the hook is called

WP_Screen::set_current_screen()
current_screen
wp-admin/includes/class-wp-screen.php 396
do_action( 'current_screen', $current_screen );

Where the hook is used (in WP core)

Does not used.