ListView: what does highlightFollowsCurrentItem do?

[Bob64]

I am confused about the role of highlightFollowsCurrentItem in ListView. It does not appear to make any difference whether it is set. If I have focus set to enable keboard navigation, the highlight follows that no matter what. If I implement setting of the currentIndex in a MouseArea in my ListView delegate, the highlight follows the mouse selection whether or not highlightFollowsCurrentItem is set.

What is it that I am missing?