The documentation section Manually Creating Custom Fields provides a good description of creating fields using the module loader, including dropdowns. But how can I do the same thing for dependent dropdowns, where I need to specify a parent dropdown and…

This is a question and tutorial combined. The question is, can I do something similar to Relate inputs like Enum (dropdown) inputs? So after some scrounging around and figuring out of some custom features and extending features, I've come across the way…