Enabling Qt::AA_CompressTabletEvents causes tablet input events to misbehave

The issue can be reproduced with the default Tablet Example in Qt Creator. If one enables the Qt::AA_CompressTabletEvents attribute, the input events result in a sudden jump in the position of the first few input events after the pen has been pressed on the screen. This results in the strokes generated to have strange artifacts.

For example, below is a screenshot of some diagonal strokes drawn with the attribute enabled. As you can see, at the beginning of many strokes there is a sudden change in direction caused by the issue at hand.

And here is a screenshot of diagonal strokes using the same routine but without the attribute enabled:

which shows no visibile artifacts at the beginning of the strokes.

I have been able to reproduced this rather consistently using a Wacom tablet on Linux (on Windows things seem to work as expected).