function rfi_post_types_input_renderer()
{
    $option = rfi_return_post_types_option();
    $post_types = get_post_types(array('public' => true), 'objects');
    foreach ($post_types as $type => $obj) {
        if (!post_type_supports($type, 'thumbnail')) {
            continue;
        }
        if (in_array($type, $option)) {
            echo '<input type="checkbox" name="rfi_post_types[]" value="' . $type . '" checked="checked">' . $obj->label . '<br>';
        } else {
            echo '<input type="checkbox" name="rfi_post_types[]" value="' . $type . '">' . $obj->label . '<br>';
        }
    }
}
/**
 * These are helpers that aren't ever registered with events
 */
function rfi_return_post_types()
{
    return apply_filters('rfi_post_types', rfi_return_post_types_option());
}