Restrict permitted artifact types in a module artifact?

If I define an artifact type of module I can define "Preferred Module Content" but not exclude artifact types - this is creating chaos because end users can add any type of artifact to any type of module in a project when editing/creating a new artifact - all they need do is select "Other artifact type or row style" then all artifact types defined in the project (which are not module types) are available for them to use.

How to lock down the list of artifact types available per module type?