What component do all KDE applications call that prevents them opening directories and files whose absolute paths are > `PATH_MAX`'s value?

In creating my solution to that question, I have ascertained that the common component appears to be QFileSystemModel.

I’ve filed bugreports.qt.io/browse/QTBUG-138251 upstream. If any dolphin developers are interested in how you could bypass PATH_MAX, I’ve provided a CPP example.