QPushButton::setMenu results invisible under Windows XP+ with Qt 4.6.0

Create a QPushButton, attach a menu to it. When the button is clicked on, the menu is invisible.

Example:
QPushButton *button = new QPushButton;
QMenu *menu = new QMenu;
menu->addAction("Test");
button->SetMenu(menu);

You can still click on the option, and when you do it shows up and works as expected. Not a huge deal, just thought I'd mention it.

If you have trouble reproducing this, please let me know and I'll make a full test case + program.