<?php

add_action('init', 'add_custom_editor_buttons');
function add_custom_editor_buttons() {
    add_filter('mce_external_plugins', 'add_fontsize_buttons');
    add_filter('mce_buttons', 'register_fontsize_buttons');
}
function add_fontsize_buttons( $plugin_array ) {
    $plugin_array['fontsize'] = TEMPLATEPATH.'/js/font-size-plugin.js';

    return $plugin_array;
}
function register_fontsize_buttons( $buttons ) {
    array_push($buttons, 'font_size_big', 'font_size_small');

    return $buttons;
}

?>