QListWidget can't set colors like in previous versions

I have the new RC of Qt 4.70 installed and the new version works different as the previous 4.6x versions. I want to colorize the background of a QListWidget. I'm using this code for this purpose:

QListWidget *Widget = new QListWidget();
Widget->addItems(QStringList() << "Item 1" << "Item 2" << "Item 3");

QPalette palette;
palette.setBrush(QPalette::Active, QPalette::Base, QColor(255, 190, 190)); // setColor don't works too
Widget->setPalette(palette);
Widget->show();

In Qt 4.6x the background will be completely red with all items, with Qt 4.70 all items will be white and the unused background will be red. I found no way to fix this with QPalette if this is a new behaviour, so I think this is a bug.
For better understanding here a picture: http://www.myimg.de/?img=Qtfd77b.png