Remove Downloads Categories / Tags widget and replace it with custom widget

gistfile1.phtml

<?php
/**
 * replace original Categories / Tags widget with custom
 */
function replace_edd_categories_tags_widget() {
	unregister_widget( 'edd_categories_tags_widget' );
	register_widget( 'custom_edd_categories_tags_widget' );
}
add_action( 'widgets_init', 'replace_edd_categories_tags_widget' );

/**
 * custom Downloads Categories / Tags Widget class
 */
class custom_edd_categories_tags_widget extends WP_Widget {
	/** Constructor */
	function custom_edd_categories_tags_widget() {
		parent::WP_Widget( false, __( 'Downloads Categories / Tags', 'edd' ), array( 'description' => __( 'Display the downloads categories or tags', 'edd' ) ) );
	}

	/** @see WP_Widget::widget */
	function widget( $args, $instance ) {
		extract( $args );

		$title      = apply_filters( 'widget_title', $instance[ 'title' ], $instance, $id );
		$tax        = $instance['taxonomy'];
		$count      = isset( $instance['count'] ) && $instance['count'] == 'on' ? 1 : 0;
		$hide_empty = isset( $instance['hide_empty'] ) && $instance['hide_empty'] == 'on' ? 1 : 0;


		global $post, $edd_options;

		echo $before_widget;
		if ( $title ) {
			echo $before_title . $title . $after_title;
		}

		do_action( 'edd_before_taxonomy_widget' );

		echo "<ul class=\"edd-taxonomy-widget\">\n";
		wp_list_categories('title_li=&taxonomy=' . $tax . '&show_count=' . $count . '&hide_empty=' . $hide_empty);
		echo "</ul>\n";

		do_action( 'edd_after_taxonomy_widget' );
		echo $after_widget;
	}

	/** @see WP_Widget::update */
	function update( $new_instance, $old_instance ) {
		$instance = $old_instance;
		$instance['title'] = strip_tags( $new_instance['title'] );
		$instance['taxonomy'] = strip_tags( $new_instance['taxonomy'] );
		$instance['count'] = isset( $new_instance['count'] ) ? $new_instance['count'] : '';
		$instance['hide_empty'] = isset( $new_instance['hide_empty'] ) ? $new_instance['hide_empty'] : '';
		return $instance;
	}

	/** @see WP_Widget::form */
	function form( $instance ) {
		// Set up some default widget settings.
		$defaults = array(
			'title'         => '',
			'taxonomy'      => 'download_category',
			'count'         => 'off',
			'hide_empty'    => 'off'
		);

		$instance = wp_parse_args( (array) $instance, $defaults ); ?>
		<p>
			<label for="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>"><?php _e( 'Title:', 'edd' ); ?></label>
			<input class="widefat" id="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>"
				   name="<?php echo esc_attr( $this->get_field_name( 'title' ) ); ?>" type="text" value="<?php echo $title; ?>"/>
		</p>
		<p>
			<label for="<?php echo esc_attr( $this->get_field_id( 'taxonomy' ) ); ?>"><?php _e( 'Taxonomy:', 'edd' ); ?></label>
			<select name="<?php echo esc_attr( $this->get_field_name( 'taxonomy' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'taxonomy' ) ); ?>">
				<option value="download_category" <?php selected( 'download_category', $taxonomy ); ?>><?php _e( 'Categories', 'edd' ); ?></option>
				<option value="download_tag" <?php selected( 'download_tag', $taxonomy ); ?>><?php _e( 'Tags', 'edd' ); ?></option>
			</select>
		</p>
		<p>
			<label for="<?php echo $this->get_field_id( 'count' ); ?>"><?php _e( 'Show Count:', 'edd' ); ?></label>
			<input <?php checked( $instance['count'], 'on' ); ?> id="<?php echo $this->get_field_id( 'count' ); ?>" name="<?php echo $this->get_field_name( 'count' ); ?>" type="checkbox" />
		</p>
		<p>
			<label for="<?php echo $this->get_field_id( 'hide_empty' ); ?>"><?php _e( 'Hide Empty Categories:', 'edd' ); ?></label>
			<input <?php checked( $instance['hide_empty'], 'on' ); ?> id="<?php echo $this->get_field_id( 'hide_empty' ); ?>" name="<?php echo $this->get_field_name( 'hide_empty' ); ?>" type="checkbox" />
		</p>
	<?php
	}
}