Did you ever wonder if it is possible to alter the order of the classes in the Class Hierarchy window? By default, the classes are sorted alphabetically but you can change this to manually. So how? Starting from your task bar, just go to Classification --> Class Hierarchy --> Sort Classes and here choose "Manually" instead of "Alphabetically".

If you go to the same menu again, you will be able to enable "Sort Mode", and now you can alter the order of your classes in the Class Hierarchy window as you like via click-and-drag! Enjoy!