mce_buttons_4 filter-hook . WP 1.0

This filter is documented in wp-includes/class-wp-editor.php

Usage

add_filter( 'mce_buttons_4', 'filter_function_name_9200', 10, 2 );
function filter_function_name_9200( $array, $string ){
	// filter...

	return $array;
}

$array

-

$string

-

Where the hook is called

$toolbar4 = apply_filters( 'mce_buttons_4', array(), 'classic-block' );

$mce_buttons_4 = apply_filters( 'mce_buttons_4', array(), $editor_id );

Where in WP core the hook is used WordPress