How to translate widget title

Add following code in theme’s functions.php:

function translate_title($title) {
 return __($title);
}
add_filter('widget_title', translate_title);

If custom widget does not react to this filter, shall suggest this feature for next release or hack it in widget.php:

function widget($args, $instance) {
 // add this before echoing title
 $instance['title'] = apply_filters('widget_title', $instance['title']);
}