This recipe made two function calls to register meta boxes with the post and page editors. This concept does not expand well to register a custom section with all the post types, since custom types created by other plugins are not known. Thankfully, there is an easy way to get an array of all the post types that can be used to associate the new meta box with all the post editors, using a quick foreach loop.

The following code shows how the ch5_psl_register_meta_box function can be re-written to associate the new box with all the post types:

function ch5_psl_register_meta_box() { 
    $post_types = get_post_types( array(), 'objects' ); 
    foreach ( $post_types as $post_type ) { 
        add_meta_box( 'ch5_psl_post_source_meta_box', 
                      'Post/Page Source', 
                      'ch5_psl_source_meta_box', 
                      $post_type->name, 'normal' );  
    } 
}