QGraphicsView and QMouseMove Event

Question

i have a borderless (no title bar) QWidget window with a QGraphicsView inside. I've overwritten mousePressEvent and mouseMoveEvent for move the window on the desktop, but when i press on the QGraphicsView this not works.

Below, the code of mousePressEvent and mouseMoveEvent:

void Widget::mousePressEvent(QMouseEvent *evt)
{
    oldPos = evt->globalPos();
}

void Widget::mouseMoveEvent(QMouseEvent *evt)
{
    const QPoint delta = evt->globalPos() - oldPos;
    move(x() + delta.x(), y() + delta.y());
    oldPos = evt->globalPos();
}

I also overwritten with the same code:

void mousePressEvent(QGraphicsSceneMouseEvent *evt); void mouseMoveEvent(QGraphicsSceneMouseEvent *evt);

i tried with:

setInteractive(false);
setDragMode(scrollHandDrag);

but nothing!

is there a way to solve this?