wp_add_editor_classic_theme_styles() │ WP 6.1.0

Deprecated since 6.8.0 Styles are enqueued, not printed in the body element.. It is no longer supported and may be removed in future releases. It is recommended to replace this function with the same one.

Loads classic theme styles on classic themes in the editor.

This is used for backwards compatibility for Button and File blocks specifically.

No Hooks.

Returns

Array. A filtered array of editor settings.

Usage

wp_add_editor_classic_theme_styles( $editor_settings );
$editor_settings(array) (required)
The array of editor settings.

Changelog

Since 6.1.0 Introduced.
Since 6.2.0 Added File block styles.
Deprecated since 6.8.0 Styles are enqueued, not printed in the body element.

wp_add_editor_classic_theme_styles() code WP 6.9.1

wp-includes/deprecated.php 
function wp_add_editor_classic_theme_styles( $editor_settings ) {
	_deprecated_function( __FUNCTION__, '6.8.0', 'wp_enqueue_classic_theme_styles' );

	if ( wp_theme_has_theme_json() ) {
		return $editor_settings;
	}

	$suffix               = wp_scripts_get_suffix();
	$classic_theme_styles = ABSPATH . WPINC . "/css/classic-themes$suffix.css";

	/*
	 * This follows the pattern of get_block_editor_theme_styles,
	 * but we can't use get_block_editor_theme_styles directly as it
	 * only handles external files or theme files.
	 */
	$classic_theme_styles_settings = array(
		'css'            => file_get_contents( $classic_theme_styles ),
		'__unstableType' => 'core',
		'isGlobalStyles' => false,
	);

	// Add these settings to the start of the array so that themes can override them.
	array_unshift( $editor_settings['styles'], $classic_theme_styles_settings );

	return $editor_settings;
}