Thread:Extension talk:CategoryTree/How to hide subcategories in "Special: Categories" page?

Don't know if it's supposed to work this way, but the Special:Categories page lists categories and subcategories. When a category is added to another category page to convert the category to a subcategory, I need it to disappear from the Special:Categories page. It's confusing to see subcategories appear in the same list as the top level categories.

Is my setting wrong, or is this the default setting? If this is the norm, is it possible to hide subcategories on the Special:Categories page?