How to associate application with existing file types using WiX installer?

Question

Related to this: How to register file types/extensions with a WiX installer? but not a duplicate.

I need to handle existing file types (.jpg files).

I do not

Answer 1

Here's a full, complete example with a bit more detail and cleaner code than in the linked question and should provide a better answer. Quite timely as I've recently finished porting the code posted previously, to use proper ProgId elements so this is fresh in my mind ;)

In regards to the 'what here', you can pretty much use whatever you like :)