Wrong z-buffer values when expanding a state

[GoogleCodeExporter]

When expanding a state by clicking the little "+" button, it overlaps with 
other states/transitions/labels. Those elements might be painted in front of 
the expanded state, which makes the entry/exit actions unreadable.

Original issue reported on code.google.com by [email protected] on 10 Mar 2015 at 10:39

[andreasmuelder]

closing as duplicate