Graphics effects not rendered properly with transformed graphics view

Applying graphics effects to items does not work properly when the graphics view is transformed.

In the attached example application (Windows, Qt 4.6 RC) a drop shadow is applied to a moving item while the graphics view is rotated -90 degrees.

• Expected outcome:
  The drop shadow is drawn properly and without any artifacts, no matter how the graphics view is transformed.

• Actual outcome:
  The position of the shadow is wrong (looks as if the graphics view had not been rotated) and there are artifacts.

Appendix A:

This may or may not be related, but a QGraphicsEffect's boundingRectFor function is called sometimes with a rect coming from logical coordinates and sometimes with a rect coming from device coordinates.

For example

1. QGraphicsItemPrivate::effectiveBoundingRect
2. calls QGraphicsEffect::boundingRect
3. calls QGraphicsEffectSource::boundingRect with system=LogicalCoordinates
4. the rect is passed to boundingRectFor

vs. (assuming that the effect is requesting the pixmap for its source item in device coordinates)

1. QGraphicsItemEffectSourcePrivate::pixmap
2. calls QGraphicsItemEffectSourcePrivate::boundingRect with system=DeviceCoordinates
3. the rect is passed to boundingRectFor

How are effects supposed to generate the correct bounding rectangle then? (e.g. if a shadow effect wants a shadow under the item with graphics view rotation == 0 but wants the shadow on the right of the
(rotated) item then the graphics view is rotated -90 degrees, then how can it do it? The return value of boundingRectFor() needs to be different in this case for logical and device coordinates.)

Appendix B:

Some pixmap filters have OpenVG-specific implementations in the OpenVG paint engine. These do not seem to care about graphics view transformations either. This could also be a source of similar issues in the future, I suppose.