Allowing/restricting content types dynamically?

It's fairly straightforward to allow/restrcict certain content types to be added to content area through attributes.

Is is it possible to control allowed/restricted content types dynamically, for example based on some other property?

Something that is really close to the OOTB look & feel as a result, allowing user to drag allowed types, not highlighting if not allowed type is dragged over etc.

Edit

I think I should be able to create MetadataExtender that sets the AllowedTypes property. Is this right?