QAbstractItemView::SingleSelection no way to interactively deselect item

When an itemview has selectionMode set to SingleSelection, the view initially has no selection. As soon as a selection is made, there is no way to interactively (with mouse/keyboard) deselect that item. Only by calling clearSelection() can this be done.

It should be possible for the user to clear the selection by clicking in an empty area of the viewport or by ctrl+clicking the selected item, just as in ExtendedSelection mode.