Widgets in a QGraphicsProxyWidget jump in layout on Mac Carbon.

QWidgets via QGraphicsWidgetProxy do not layout properly on Carbon.
On almost every load one of the widgets in the layout will jump positions after about a second.
On Cocoa the widgets stay still (as expected)

#include <QtGui>

int main(int argc, char *argv[])
{
QApplication app(argc, argv);

QWidget *panel = new QWidget();
QVBoxLayout *layout = new QVBoxLayout(panel);
panel->resize(600,600);

layout->addWidget(new QLabel("Run this a couple of times under Carbon and Cocoa, in Cocoa the proxys do not move."));

QGraphicsScene *scene = new QGraphicsScene(panel);
QGraphicsView *view = new QGraphicsView(scene);
layout->addWidget(view);

QLineEdit *lineEdit1 = new QLineEdit("edit 1 is going to hide now.");
QGraphicsProxyWidget *item1 = new QGraphicsProxyWidget();
item1->setWidget(lineEdit1);
item1->setPos(10, 10);
scene->addItem(item1);

QLineEdit *lineEdit2 = new QLineEdit("edit 2");
QGraphicsProxyWidget *item2 = new QGraphicsProxyWidget();
item2->setWidget(lineEdit2);
item2->setPos(10, 40);
scene->addItem(item2);

QSlider *slider = new QSlider(Qt::Horizontal);
QGraphicsProxyWidget *item3 = new QGraphicsProxyWidget();
item3->setWidget(slider);
item3->setPos(10, 70);
scene->addItem(item3);

panel->show();
return app.exec();
}