Testing image size filter for post editor

gistfile1.aw

<?php
// test images
add_image_size( 'ducks', 350, 350, true );
add_image_size( 'cows', 750, 150, true );


 //this function does not work and acts very wacky
    function add_image_check(){

	global $_wp_additional_image_sizes;

        //default array
        $default = array(
                         'thumbnail' => __('Thumbnail'), 
                         'medium'    => __('Medium'), 
                         'large'     => __('Large'), 
                         'full'      => __('Full Size') 
                       );
       
        //array from add_image_size
        $new = $_wp_additional_image_sizes;

        //merge the arrays
	$result = array_merge($default, array_keys($new));

	return $result;
 };

add_filter('image_size_names_choose', 'add_image_check' );

//#########################################################

//this function works
 function add_image_check_part2(){

	global $_wp_additional_image_sizes;

       //default array with hardcoded values fro add_image_size
        $default = array(
                          'thumbnail' => __('Thumbnail'), 
                          'medium'    => __('Medium'), 
                          'large'     => __('Large'), 
                          'full'      => __('Full Size'), 
                          'ducks'     => __('Ducks'), 
                          'cows'      => __('Cows') 
                        );

      return $default

};

add_filter('image_size_names_choose', 'add_image_check_part2' );




?>