Wordpress widget title as class name

Sometimes we get a layout that need a css style for each widget title, but Wordpress doesn't have an automatic way to do this on register_sidebar(). So, we need to use this filter on functions.php to do the trick:

function widget_title_as_class($title) { 
    return '<h3 class="widget-title ' . sanitize_title($title) . '">' . $title . '</h3>';
}
add_filter('widget_title', 'widget_title_as_class');