WP & TinyMCE Styles Dropdown

wp-tinymce-styles.php

<?php

/**
 * Customize TinyMCE -- Add styles dropdown and add some custom styles. Selecting the style will add a class to the element.
 *
 **/
function my_tinymce_styles( $init ) {
	$init['theme_advanced_buttons2_add_before'] = 'styleselect';
	$init['theme_advanced_styles'] = 'Top Right Inset=insettop,Left Inset=insetleft,Right Inset=insetright';
	return $init;
}
add_filter( 'tiny_mce_before_init', 'my_tinymce_styles' );