How to find topics which are not assigned to a map ID

Perhaps I am missing something very obvious in the Edit Map IDs window, but I can't find a way to easily identify topics which have not been given a Map ID.

Initially, I selected all topics and used the auto map option for the project map file, but I am constantly adding topics and don't always remember to go straight in and assign an ID at the time of creation.

Can somebody point me in the right direction?

Thanks!

Chloe