WP_Customize_Filter_Setting example

        $this->manager->add_section(
            'add_menu',
            array(
                'type'     => 'new_menu',
                'title'    => __( 'New Menu' ),
                'panel'    => 'nav_menus',
                'priority' => 20,
            )
        );

        $this->manager->add_setting(
            new WP_Customize_Filter_Setting(
                $this->manager,
                'nav_menus_created_posts',
                array(
                    'transport'         => 'postMessage',
                    'type'              => 'option', // To prevent theme prefix in changeset.                     'default'           => array(),
                    'sanitize_callback' => array( $this, 'sanitize_nav_menus_created_posts' ),
                )
            )
        );
    }

    

'filter_type' => 'remote',
                        'capability'  => 'install_themes',
                        'panel'       => 'themes',
                        'priority'    => 5,
                    )
                )
            );
        }

        // Themes Setting (unused - the theme is considerably more fundamental to the Customizer experience).         $this->add_setting(
            new WP_Customize_Filter_Setting(
                $this,
                'active_theme',
                array(
                    'capability' => 'switch_themes',
                )
            )
        );

        /* Site Identity */

        $this->add_section(