Window decorations cause SEGFAULT after last update (on PowerPC)

[geppo61]

Hello,
due to last upgrade (apt-get dist-upgrade) I see an annoying problem using compiz (as far as it is the window manager I am using).

After some time (let's say moving around some windows) it crashes with:
gtk-window-decoration assert ...
[I am sorry but now I am at work and I don't have the workstation to report the problem correctly]

My specs are:

Machine: Apple PowerPC Quad G5 @ 2.5Ghz with 8Gb of ECC DRAM
VideoCard: a NON OPEN-FIRMWARE (i.e. a VBIOS Flashed Card x86) ATI RADEON HD9670 1GB DDR3 PCI-Express
Ubuntu MATE 16.04 Xenial Xerus

If I revert back to Software Compositor (using MARCO, so NO COMPIZ) everything is working as expected.

The OpenGL as far as I can test is working good: Quake, Quake3, GLBilliards, glxgears...

Hope this helps
---
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: powerpc
CurrentDesktop: MATE
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-08-24 (20 days ago)
InstallationMedia: Ubuntu-MATE 16.04.1 LTS "Xenial Xerus" - Release powerpc (20160719)
Package: compiz 1:0.9.12.2+16.04.20160823-0ubuntu1
PackageArchitecture: all
ProcVersionSignature: Ubuntu 4.4.0-36.55-powerpc64-smp 4.4.16
Tags: xenial xenial
Uname: Linux 4.4.0-36-powerpc64-smp ppc64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True

[geppo61 (icjtqr-gmail)]

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[geppo61 (icjtqr-gmail)]

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[geppo61 (icjtqr-gmail)]

apport information

[geppo61 (icjtqr-gmail)]

apport information

[geppo61 (icjtqr-gmail)]

..and now, after upgrading compiz today, the system has no window decorations at all. Force to use MARCO (GPU or SOFTWARE COMPOSITOR) works. No more compiz does.