Scaling of proxy widgets in QGraphicsView is not working correctly on Mac OS X

When zooming in and out the check box's the indicator doesn't scale and the selection frame of a tablewidget item behaves arbitrary. See the attached screenshots.

The attached example can be used to reproduce the issue.
Steps to reproduce:
1. select a tablewidget item to have the selection frame around
2. start zooming in and out with the cmd key + wheel

Expected result:
The checkbox indicator should increase and decrease and the tablewidget's item selection frame should also

Actual result:
The checkox's indicator is always the same size and the tablewidget's item selection frame may become really big even though the item itself is small

The issue can be reproduced only on Mac OS X and with -style macintosh. If one changes the style to e.g. fusion or windows, the issue does not reproduce. The issue is also not reproducible on Ubuntu 14.04 with -style macintosh.