--- a/wp/wp-includes/customize/class-wp-customize-background-image-setting.php	Thu Sep 29 08:06:27 2022 +0200
+++ b/wp/wp-includes/customize/class-wp-customize-background-image-setting.php	Fri Sep 05 18:40:08 2025 +0200
@@ -15,6 +15,13 @@
  * @see WP_Customize_Setting
  */
 final class WP_Customize_Background_Image_Setting extends WP_Customize_Setting {
+
+	/**
+	 * Unique string identifier for the setting.
+	 *
+	 * @since 3.4.0
+	 * @var string
+	 */
 	public $id = 'background_image_thumb';
 
 	/**