I have recently started a discussion on a developed Presentation Module.
With the help of the first users I have found out that naming a file config.php in the modules directory and including it in the lib.php file (require_once(config.php);) changes the admin section. Here is the discussion: http://moodle.org/mod/forum/discuss.php?d=37698#174253
It immediately opens the Configuration->Variables section.
Using the same file same way with a different name solves the problem.
So, is that a bug or a convention not to use config.php name in the module folders?