I'd ask this question of a forum that specializes in phpMyAdmin.
XAMPP is a server suite - We don't develop any of the applications or tools. The XAMPP team creates packages/distributions to make developing your own scripts/applications easier. Our job is to make them function correctly in their 'as installed' mode.
If someone knows about this issue, or wants to answer your question then that's a good thing, but its a really a matter for phpMyAdmin specialists. I have already given you my opinion, and I'm a MySQL developer. You would need code that controls the enumeration of databases by querying the metadata first (that's my opinion). I don't 'think' phpMyAdmin can do that out of the box. You can check the code and documentation as phpMyAdmin is also Open Source. It might even exist in some form, but you will have to look for that.http://www.phpmyadmin.net/home_page/index.php