Insert HTML to top of list widget (TEC/ECP 3.x)

add_filter('dynamic_sidebar_params', 'insert_list_widget_title_img');

function insert_list_widget_title_img($args) {
    if ('Events List' !== $args[0]['widget_name']) return $args;

    $args[0]['before_title'] .= '<span> Some special HTML sauce of your choosing </span>';
    return $args;
}