Cannot restore an iconified window when several windows of same WM_CLASS are present with Unity

[Alex]

I cannot restore an iconified window when several windows of same WM_CLASS are present with Unity.

If there is only an iconified window, it works fine, simply restores after a click in dock on its icon.
If there are an iconified and another window in normal state, then it is tricky, I have to click several times on the dock icon to restore it.
If there are an iconified window and two or more windows in normal state I am unable to restore it with Unity DE.

Sample attached, to reproduce the issue compile and run it with gcc main.c -lX11 -o main && ./main

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: unity 7.2.3+14.04.20140826-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-40.69-generic 3.13.11.10
Uname: Linux 3.13.0-40-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CurrentDesktop: Unity
Date: Mon Dec 1 20:36:37 2014
InstallationDate: Installed on 2013-11-09 (387 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
SourcePackage: unity
UpgradeStatus: Upgraded to trusty on 2014-04-18 (227 days ago)