Issue #2248799 by amitgoyal, c31ck, Wim Leers: Fix docs for system_sort_themes

modules/system/system.admin.inc

@@ -950,7 +950,11 @@ function system_sort_modules_by_info_name($a, $b) {
 }
 
 /**
- * Array sorting callback; sorts modules or themes by their name.
+ * Sorts themes by their names, with the default theme listed first.
+ *
+ * Callback for uasort() within system_themes_page().
+ *
+ * @see system_sort_modules_by_info_name().
  */
 function system_sort_themes($a, $b) {
   if ($a->is_default) {