QGraphicsItem dragging on high Dpi screen makes the item partly disappear.

See the example project.

If the blue rectangle is dragged fast on high Dpi screen it partly disappears.

This does not occur with non-high Dpi screen.

If GraphicsView::setViewportUpdateMode(QGraphicsView::FullViewportUpdate); is used the rectangles seem to stay visible on both screen types.

Users example(qr_test.zip) has also been attached.

Here is the user comment:

"If you run the example and drag a rectangle fast in a repeatedly circular motion you should notice artefacts.
it doesnt look like a perfect rectangle anymore - partly disjoint. It seems that if I add the "invalidate()" to "tJvGvScene::mouseMoveEvent()" that the artefact disappears."