I use Japanese character.
I updated WPP to 2.1.3 from 2.1.0, and my widget is garbled, too.
It works properly with 2.1.0.
I replaced $instance['title'] = htmlspecialchars( stripslashes(strip_tags( $new_instance['title'] )), ENT_QUOTES );
with $instance['title'] = htmlspecialchars( stripslashes(strip_tags( $new_instance['title'] )), ENT_QUOTES, 'UTF-8', FALSE );
, but a problem was not settled.