Cannot change the look of QMenu::tear-off using stylesheets

It appears that customizing the appearance of the tear-off handle of a QMenu using stylesheets doesn't work. The documentation (http://doc.qt.nokia.com/4.6/stylesheet-reference.html) seems to indicate it's possible: "The tear-off is styled using the ::tear-off" (on styling QMenu).

Here's what I've tried:

QMenu::tear-off

{ background-color: green; color: red; border: 10px solid yellow; }

But this has no effect, neither on Windows (Vista x64) nor on Mac OS X (10.4).

The documentation is very sparse on how to style this specific subcontrol, so I might not be doing the right thing.