gcompris water cycle doesn't recognise all possible actions

[Robert Osmond]

Description of problem:
in gcompris the water cycle (and maybe other sub games too) doesn't recognize all possible stations to click.
It isn't possible to finish the water cycle.

Version-Release number of selected component (if applicable):
Xenial / Ubuntu 16.04 beta

How reproducible:
always

Steps to Reproduce:
1. start gcompris
2. go in the third category (on the left side) to the physical experiments
3. start the 3rd SubGame (water cycle)
4. click the sun, afterwards the clouds, and so on
5. the power plant on water to generate electricity doesn't reacts -> so the water cycle isn't possible to fulfill.
6. sometimes the sun isn't even clickable

Actual results:
the active elements (eg, the sun and the power plant to generate electricity) are not clickable

Expected results:
all stations on water cycle must be clickable to fulfill the task

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: gcompris 15.02-1.1ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-16.32-generic 4.4.6
Uname: Linux 4.4.0-16-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.20.1-0ubuntu1
Architecture: amd64
CurrentDesktop: XFCE
Date: Wed Apr 6 21:26:42 2016
ExecutablePath: /usr/games/gcompris
InstallationDate: Installed on 2016-04-02 (4 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Beta amd64 (20160401)
ProcEnviron:
 LANGUAGE=en_AU:en
 PATH=(custom, no username)
 XDG_RUNTIME_DIR=<set>
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
SourcePackage: gcompris
UpgradeStatus: No upgrade log present (probably fresh install)