show posts names and links in the sidebar list as categories child

i’m using this plugin to show an exapandable/collapsible widget-menu in my sidebar.
http://wordpress.org/extend/plugins/folding-category-widget
it works very well!

the question, not directly connected with this plugin, is: how can i also show in the list, all posts related to a category (title + a href)?

for example:

category A 
         post1
         post2

category B
         post3
         post4

category C
         post5

thanks a lot in advance.

Well the simplest way I can think of is something like this…

<ul class="categories">
<?php
    $categories = get_categories(); //can add parameters here to swtich the order, etc;
    if(!empty(categories)):
        foreach($categories as $i => $category):
?>

<li class="category">
    <span><?php echo $category->name ?></span>

        <?php

        query_posts('posts_per_page=-1&cat=" . $category->term_id);
        if ( have_posts() ) :
        ?>
        <ul class="posts">
        <?php
             while ( have_posts() ) : the_post(); //we make a loop for each category, 
        ?>
            <li class="post">
                <a href="https://wordpress.stackexchange.com/questions/5270/<?php the_permalink();?>"><?php the_title();?></a>
            </li>
            <?php endwhile; ?>
        </ul>
            <?php endif; ?>
        <?php wp_reset_query(); ?>
</li>
        <?php endforeach; endif; ?>
</ul>

Warning: this is untested code, but it should work just fine. (Just add it to your sidebar.php file or wherever you generate your sidebar.)