// Get array of post info.
	$cat_posts = new WP_Query("showposts=" . $instance["num"] . "&cat=" . $instance["cat"] . '&orderby=date&order=asc');

The Category Posts Widget is very good for showing a certain # of posts in a particular category using a widget that displays on every page. However, if you only want to show the posts for the current category in the sidebar, then add this code to your sidebar.php file:

<?php
 $sidebar_related_query = new WP_Query('cat=' . $sidebar_cat_id . '&showposts=5&offset=0&orderby=post_date&order=desc');
 while ($sidebar_related_query->have_posts()) : $sidebar_related_query->the_post();
 $do_not_duplicate = $post->ID;
 ?>

 <div id=”post-<?php the_ID(); ?>">
 <a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a>
 </div>

 <?php endwhile; ?>

http://www.moongoosedesigns.com/customizing-post-sort-order-using-the-category-posts-widget/

Edit widget or display current category in sidebar.php

Customizing Post Sort Order Using the Category Posts Widget

wordpress

PHP