mod/glossary/settings.php abuses admin_setting_heading to put some icons on the settings screen. That is pretty evil already. However, what makes it really, really wicked is that to do this, it refers to $CFG->pixpath. That means that we refer to $CFG->pixpath in admin_get_root. However, in several places we need to call admin_get_root to get the admin tree before we have initialised all the information about the current theme. I think that this should be a custom admin_setting class, so we only create the HTML on output. (Assigning to Petr, since he originally wrote this code. However, it is not really his fault.)