One consequence of adding a Microblog feed to this site was that a lot of post IDs were showing up in the Recent Posts widget. It turns out that if a post is missing a title, the widget falls back to just displaying the ID number. Sad!

It turns out that customizing the widget was fairly straightforward. Since I already have a child theme set up, all I had to do was copy the widget class into the child theme, make my tweaks, and add a few lines to my functions.php file.

The functions.php changes were incredibly straightforward. I added the following lines:

// Include Recent Posts Excluding Category widget
include("class-wp-widget-recent-posts-exclude-cat.php");
add_action( 'widgets_init', function(){
    register_widget( 'WP_Widget_Recent_Posts_Exclude_Cat' );
});

… where class-wp-widget-recent-posts-exclude-cat.php is the class of my new widget.

You can see the custom version of the widget on Github. The essence of the changes I made was to add one more filter to the code that retrieves the list of 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,
            'cat'                 => $exclude_cat
        ) ) );

The last condition, 'cat' => $exclude_cat, is the one I added. If you pass a negative value to the cat filter, that becomes a category exclusion. In my case, I want to exclude the Micro category, which has an ID of 104, so $exclude_cat = -104.