Limit length of headline in Editor

You could add this function :

add_action('publish_post', 'wpse_105297_max_char');
function wpse_105297_max_char() {
   global $post;
   $title = $post->post_title;
   if (strlen($title) >= 100 )
    wp_die( "The max lenght is 100 for title" );
 }

This will prevent users from using too much longer titles.