Custom post status

Question

Have you read Custom Status on codex.wordpress.org/Post_Status?

NOTICE:
This function does NOT add the registered post status to the admin panel. This functionality is pending future development. Please refer to Trac Ticket #12706. Consider the action hook post_submitbox_misc_actions for adding this parameter.

Adding a custom status to WordPress is done via the register_post_status() function. This function allows you to define the post status and how it operates within WordPress.

function custom_post_status(){
    register_post_status( 'unread', array(
        'label'                     => _x( 'Unread', 'post' ),
        'public'                    => true,
        'exclude_from_search'       => false,
        'show_in_admin_all_list'    => true,
        'show_in_admin_status_list' => true,
        'label_count'               => _n_noop( 'Unread <span class="count">(%s)</span>', 'Unread <span class="count">(%s)</span>' ),
    ) );
}
add_action( 'init', 'custom_post_status' );

Although it doesn’t look like custom post status is supported in the admin publish metabox but maybe in a future patch.