Hello - Can you make the use of <h2> . $title . '</h3>';
Row 76 in list_cat_posts_widget.php configurable?
The Thesis Theme uses H3 for its widgets. All my other theme widgets seem to understand the theme settings for sidebar widget titles and show them as h3, not H2. I don't know if the use of a particular heading tag is standard, my guess is h2 is more normal, or if there is a way to have it use what ever is configured for the theme.
All I know is I have tweaked your code to say H3 for my site, after an upgrade I need to remember to change it again. If this was configurable my changes would hold after an upgrade.