If Rack Lock is on, you can still add modules by clicking them in the search result. If the rack is full, the cat will freak out on you. To remove those unwanted modules or to clean up the mess (pleasing the cat) you need to turn off Rack Lock.

This is a very minor annoyment and by no means a dealbreaker. Just wanted to report in case time will allow for a fix at some point in time.

Thanks for reporting, that should now be fixed.