I want to set the small windows without window title bar in the embeddeddialogs example , so I add setWindowFlags(Qt::FramelessWindowHint) in the CustomProxy's construct function.

The windows then shows without window title bar, but another problem comes : the windows CAN NOT show in front of its nearby windows any move when mouse moving over it , but always zooming behind them.

Why does this happen?

CustomProxy::CustomProxy(QGraphicsItem *parent, Qt::WindowFlags wFlags)
: QGraphicsProxyWidget(parent, wFlags), popupShown(false), currentPopup(0)
timeLine = new QTimeLine(250, this);
connect(timeLine, SIGNAL(valueChanged(qreal)),
this, SLOT(updateStep(qreal)));
connect(timeLine, SIGNAL(stateChanged(QTimeLine::State)),
this, SLOT(stateChanged(QTimeLine::State)));

this->setWindowFlags(Qt::FramelessWindowHint); // Added