Can't style QHeaderView::section:checked when using QTreeWidget

I seem unable to change the background color (or any other property) of a QHeaderView section using the QHeaderView::section:checked selector using Qt 4.7.0. Here's the relevant code:

QHeaderView::section:checked
{
    background-color: red;
}

There's a detailed account of this (potential) bug and a follow-up discussion in this post on Qt Centre.