fgrlx driver makes screen black after unplug the external monitor

[Fran Diéguez]

External monitor goes black after unplug it using GNOME-Shell

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: xserver-xorg 1:7.7+7ubuntu2
ProcVersionSignature: Ubuntu 3.16.0-20.27-generic 3.16.3
Uname: Linux 3.16.0-20-generic x86_64
NonfreeKernelModules: fglrx wl
ApportVersion: 2.14.7-0ubuntu3
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: GNOME
Date: Mon Oct 6 21:02:03 2014
DistUpgraded: Fresh install
DistroCodename: utopic
DistroVariant: ubuntu
DkmsStatus:
 bcmwl, 6.30.223.248+bdcom, 3.16.0-20-generic, x86_64: installed
 fglrx-updates-core, 14.201, 3.16.0-20-generic, x86_64: installed
 virtualbox, 4.3.14, 3.16.0-20-generic, x86_64: installed
ExtraDebuggingInterest: Yes
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Seymour [Radeon HD 6400M/7400M Series] [1002:6760] (prog-if 00 [VGA controller])
   Subsystem: Apple Inc. Device [106b:00e1]
InstallationDate: Installed on 2014-09-19 (17 days ago)
InstallationMedia: Ubuntu-GNOME 14.10 "Utopic Unicorn" - Alpha amd64 (20140917)
MachineType: Apple Inc. MacBookPro8,2
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-20-generic root=UUID=57f6fdf7-aa44-4f18-b92d-9ce76414c598 ro quiet splash vt.handoff=7
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
XorgConf:

dmi.bios.date: 01/24/12
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP81.88Z.0047.B27.1201241646
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-94245A3940C91C80
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookPro8,2
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-94245A3940C91C80
dmi.modalias: dmi:bvnAppleInc.:bvrMBP81.88Z.0047.B27.1201241646:bd01/24/12:svnAppleInc.:pnMacBookPro8,2:pvr1.0:rvnAppleInc.:rnMac-94245A3940C91C80:rvrMacBookPro8,2:cvnAppleInc.:ct10:cvrMac-94245A3940C91C80:
dmi.product.name: MacBookPro8,2
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
version.compiz: compiz N/A
version.fglrx-installer: fglrx-installer N/A
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.56-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.3.0-0ubuntu2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.3.0-0ubuntu2
version.xserver-xorg-core: xserver-xorg-core 2:1.16.0-1ubuntu1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.0-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.4.0-2ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.914-1~exp1ubuntu3
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu2
xserver.bootTime: Mon Oct 6 21:01:38 2014
xserver.configfile: /etc/X11/xorg.conf
xserver.errors:
 open /dev/dri/card0: No such file or directory
 AIGLX error: failed to open /usr/X11R6/lib64/modules/dri/fglrx_dri.so, error[/usr/X11R6/lib64/modules/dri/fglrx_dri.so: cannot open shared object file: No such file or directory]
 AIGLX error: failed to open /usr/lib64/dri/fglrx_dri.so, error[/usr/lib64/dri/fglrx_dri.so: cannot open shared object file: No such file or directory]
 AIGLX error: failed to open /usr/X11R6/lib/modules/dri/fglrx_dri.so, error[/usr/X11R6/lib/modules/dri/fglrx_dri.so: cannot open shared object file: No such file or directory]
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.16.0-1ubuntu1
xserver.video_driver: fglrx