It would be nice if one could configure to omit the QXyzPrivate classes from the list of autocompletion suggestions. Unless you're hacking on Qt itself, it's very unlikely that you will use those in client code. Another acceptable solution would be to move those to end of the list.

If it's feasible, one could add some pattern/regex describing the private class names that should be moved out of the way. That would be handy for getting rid of QXyzPrivate, but leaving one's own private classes in the completer.