fullscreen windows get focus randomly during changing viewport

[Irbis]

Preconditions:
cube and rotate plugins have to be active, vertical desktop size equals 4

How to reproduce:
Open two fullscreen windows on the same viewport, for example google chrome:

google-chrome-stable --new-window --kiosk www.google.com
google-chrome-stable --new-window --kiosk www.askubuntu.com

There are two windows. A window opened last, is visible and has a focus which is correct. When cube is rotated to another viewport and then back to a viewport which contains fullscreen windows sometimes the first fullscreen window gets focus and is visible, sometimes the second. It is totally random behaviour.

Expected result: after rotation to another viewport and back a focus and drawing order should be preserved.

Version: I first noitced that bug when using Compiz 0.9.10.0 and it is still present.