Extend Recent Posts Widget with Thumbnail Image and others

Extend Recent Posts Widget.php

 /**
  * Extend Recent Posts Widget
  *
  * Adds different formatting (images) to the default WordPress Recent Posts Widget
  */
 Class Ns_Recent_Posts_Widget extends WP_Widget_Recent_Posts {


         function widget($args, $instance) {

                 if ( ! isset( $args['widget_id'] ) ) {
                 $args['widget_id'] = $this->id;
             }

             $title = ( ! empty( $instance['title'] ) ) ? $instance['title'] : __( 'Recent Posts' );

             /** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
             $title = apply_filters( 'widget_title', $title, $instance, $this->id_base );

             $number = ( ! empty( $instance['number'] ) ) ? absint( $instance['number'] ) : 5;
             if ( ! $number )
                 $number = 5;
             $show_date = isset( $instance['show_date'] ) ? $instance['show_date'] : false;

             /**
              * Filter the arguments for the Recent Posts widget.
              *
              * @since 3.4.0
              *
              * @see WP_Query::get_posts()
              *
              * @param array $args An array of arguments used to retrieve the recent posts.
              */
             $r = new WP_Query( apply_filters( 'widget_posts_args', array(
                 'posts_per_page'      => $number,
                 'no_found_rows'       => true,
                 'post_status'         => 'publish',
                 'ignore_sticky_posts' => true
             ) ) );

             if ($r->have_posts()) :
             ?>
             <?php echo $args['before_widget']; ?>
             <?php if ( $title ) {
                 echo $args['before_title'] . esc_attr( $title ) . $args['after_title'];
             } ?>
             <ul>
             <?php while ( $r->have_posts() ) : $r->the_post(); ?>
                 <li>
                     <?php the_post_thumbnail(); ?>
                     <a href="<?php the_permalink(); ?>"><?php get_the_title() ? the_title() : the_ID(); ?></a>
                 <?php if ( $show_date ) : ?>
                     <span class="post-date"><?php echo get_the_date(); ?></span>
                 <?php endif; ?>
                 </li>
             <?php endwhile; ?>
             </ul>
             <?php echo $args['after_widget']; ?>
             <?php
             // Reset the global $the_post as this query will have stomped on it
             wp_reset_postdata();

             endif;
         }
 }
 function ns_recent_widget_registration() {
   unregister_widget('WP_Widget_Recent_Posts');
   register_widget('Ns_Recent_Posts_Widget');
 }
 add_action('widgets_init', 'ns_recent_widget_registration');