QTreeView details: what are viewItems?

[neuronet]

Within the Qt source the private implementation is usually in a file named blah_p.h for a class blah with its public API in blah.h. The private header is #included into the implementation file blah.cpp but not inthe public header or user programs.

I would not worry too much about the internals of the views and models if all you want to do is use them.

Thanks a lot for the specifics, that is helpful, though I am frankly still a bit lost.

tl;dr : Good point: my goal is just to use this software, not become a developer. If it really is important I learn the internals, I will need to learn Qt for real (c++).

The problem is, as I try to explain to other PySide users what is going on underneath, I often have no idea. For instance "Why the redundancy between model.data() and index.data(): why not always use one or the other?" It is frustrating to not be able to go in and figure such things out easily on my own. c++ code is a labyrinthine mystery to me for the most part. For some things, going to the source is really helpful. With QTreeView, it has been mostly frustrating.