QGraphicsView rubber band selection rectangle not visible - qt

Question

I have a QGraphicsView widget with lots of items on scene. I am panning the view on ctr+left mouse click and zooming it to rectangle of rubber band created with left mouse button drag. I am not able to see rubber band selection rectangle (dotted lines) whereas rubberband selection functionality works fine. Can anybody help me understand this?.I use these flags in my view:
setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
setViewportUpdateMode(QGraphicsView::SmartViewportUpdate);
setRenderHints(QPainter::HighQualityAntialiasing | QPainter::SmoothPixmapTransform);
setOptimizationFlag(QGraphicsView::DontSavePainterState,true);
setCacheMode(QGraphicsView::CacheBackground);
setOptimizationFlag(QGraphicsView::DontAdjustForAntialiasing);
setViewport(new QGLWidget);
below are my event handlers.
Mouse press event handler:
void MyView::mousePressEvent(QMouseEvent* event)
{
if(event->button()==Qt::LeftButton)
{
if(event->modifiers()==Qt::ControlModifier)
{
setDragMode(QGraphicsView::NoDrag);
m_rubberBandActive = false;
mousepressed=true;
m_lastDragPos = event->pos();
return;
}
else
{
setDragMode(QGraphicsView::RubberBandDrag);
m_rubberBandOrigin = event->pos();
m_rubberBandActive = true;
}
}
event->accept();
}
else
{
QWidget::mousePressEvent(event);
}
}
Mouse move event:
void MyView::mouseMoveEvent(QMouseEvent* event)
{
if(mousepressed)
{
QPointF delta = mapToScene(event->pos()) - mapToScene(m_lastDragPos);
this->panView(delta);
m_lastDragPos = event->pos();
return;
}
event->accept();
}
Mouse release event Handler:
void MyView::mouseReleaseEvent(QMouseEvent *event)
{
if (m_rubberBandActive)
{
QPoint rubberBandEnd = event->pos();
QRectF zoomRectInScene = QRectF(mapToScene(m_rubberBandOrigin),mapToScene(rubberBandEnd));
fitInView(zoomRectInScene, Qt::KeepAspectRatio);
m_rubberBandActive = false;
}
mousepressed=false;
event->accept();
}
Pan view:
void MyView::panView(QPointF delta)
{
QPoint viewCenter(viewport()->width() / 2 + delta.x(), viewport()->height() / 2 + delta.y());
QPointF newCenter = mapToScene(viewCenter);
centerOn(newCenter);
}