wp_ajax_closed_postboxes()

function wp_ajax_closed_postboxes() {
	check_ajax_referer( 'closedpostboxes', 'closedpostboxesnonce' );
	$closed = isset( $_POST['closed'] ) ? explode( ',', $_POST['closed']) : array();
	$closed = array_filter($closed);

	$hidden = isset( $_POST['hidden'] ) ? explode( ',', $_POST['hidden']) : array();
	$hidden = array_filter($hidden);

	$page = isset( $_POST['page'] ) ? $_POST['page'] : '';

	if ( $page != sanitize_key( $page ) )
		wp_die( 0 );

	if ( ! $user = wp_get_current_user() )
		wp_die( -1 );

	if ( is_array($closed) )
		update_user_option($user->ID, "closedpostboxes_$page", $closed, true);

	if ( is_array($hidden) ) {
		$hidden = array_diff( $hidden, array('submitdiv', 'linksubmitdiv', 'manage-menu', 'create-menu') ); // postboxes that are always shown
		update_user_option($user->ID, "metaboxhidden_$page", $hidden, true);
	}

	wp_die( 1 );
}