gnome-shell crashed with SIGABRT in g_assertion_message()

[Michael]

This happened while running VirtualBox in dual monitor (guest and host) full-screen mode, shortly after starting the virtual machine.

ProblemType: Crash
DistroRelease: Ubuntu 14.10
Package: gnome-shell 3.12.2-1ubuntu4
ProcVersionSignature: Ubuntu 3.16.0-11.16-generic 3.16.1
Uname: Linux 3.16.0-11-generic x86_64
ApportVersion: 2.14.6-0ubuntu2
Architecture: amd64
CurrentDesktop: GNOME
Date: Fri Aug 29 09:03:08 2014
DisplayManager: lightdm
ExecutablePath: /usr/bin/gnome-shell
GsettingsChanges:
 b'org.gnome.desktop.interface' b'gtk-im-module' b"'gtk-im-context-simple'"
 b'org.gnome.desktop.interface' b'scaling-factor' b'uint32 1'
InstallationDate: Installed on 2014-08-01 (28 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcCmdline: /usr/bin/gnome-shell
Signal: 6
SourcePackage: gnome-shell
StacktraceTop:
 g_assertion_message () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
 g_assertion_message_expr () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
 meta_window_unmanage () from /usr/lib/libmutter.so.0
 ?? () from /usr/lib/libmutter.so.0
 ?? () from /usr/lib/libmutter.so.0
Title: gnome-shell crashed with SIGABRT in g_assertion_message()
UpgradeStatus: Upgraded to utopic on 2014-08-28 (0 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo vboxusers

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #1351011, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.