Multitouch not working correctly (widgets on Windows)

The multitouch is not working properly in Qt 4.8.4. The dials example (examples\though\dials) can be used to reproduce this issue with the following steps:

1) On a touch screen touch one dial with one finger
2) Touch another dial with a finger while keeping the first finger still touching the dial at 1) (both working ok if both are moved, if the dial in 1) is not moved then the other dial is really slow)
3) Remove the finger from the first dial (the one at step 1) ), this will cause the dial at step 2) to also stop working

It would be expected that the dial at step 2) can still be used even if the first finger is lifted up.