From the MSDN docs on hit testing:

Version 4.70. Receives the index of the matching subitem. When hit-testing an item, this member will be zero.

So, that is to be expected.

Sorry, but I don't understand that. I'm hit-testing a subitem, not an item, but I still get zero.

Might make a good RFE, hint, hint.

You asked for it!

By the way, I have in-place editing for subitems working, and using a combo box for a subitem.  I am pretty happy with the way they work.  I just need to tidy up a few details and then I'll post on the list here with information.

Looking forward to seeing it.