Plugging in HDMI during login temporarily revealed screen

I had left my computer to get water, and when I returned it had gone black, as it normally does. I tapped at the keys, used my mousepad, the normal to get it awake again. At some point, I plugged in an HDMI cable connected to a Dell moniter that I have connected to this computer before. I am not sure if the screen was black, or at the login screen, when I did this. I began typing in my password. As I did so, the connection to the monitor, which had been black, seemed to activate, and I saw the login screen on the larger monitor. However, I also saw the pages that I had open on my laptop screen. This was before login was complete.

I am aware that this probably doesn't represent a serious security risk, but it is problematic and potentially damaging.

I have no evidence that the fault is xorgs, but I was told to put all vision problems
under the xorg package.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: xorg 1:7.7+1ubuntu4
Uname: Linux 3.4.0 i686
.tmp.unity.support.test.0:

ApportVersion: 2.9.2-0ubuntu8.3
Architecture: i386
BootLog:

CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
Date: Fri Aug 23 10:44:18 2013
DistUpgraded: Fresh install
DistroCodename: raring
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0106] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0106]
MachineType: GOOGLE Parrot
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no username)
 XDG_RUNTIME_DIR=<set>
 SHELL=/bin/sh
ProcKernelCmdLine: cros_secure console=tty1 debug verbose root=/dev/sda7 rootwait rw lsm.module_locking=0
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/10/2012
dmi.bios.vendor: coreboot
dmi.bios.version: Google_Parrot.2685.37.0
dmi.chassis.type: 3
dmi.chassis.vendor: GOOGLE
dmi.modalias: dmi:bvncoreboot:bvrGoogle_Parrot.2685.37.0:bd09/10/2012:svnGOOGLE:pnParrot:pvr1.0:cvnGOOGLE:ct3:cvr:
dmi.product.name: Parrot
dmi.product.version: 1.0
dmi.sys.vendor: GOOGLE
version.compiz: compiz 1:0.9.9~daily13.06.19~13.04-0ubuntu1
version.libdrm2: libdrm2 2.4.43-0ubuntu1.1
version.libgl1-mesa-dri: libgl1-mesa-dri 9.1.3-0ubuntu0.3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 9.1.3-0ubuntu0.3
version.xserver-xorg-core: xserver-xorg-core 2:1.13.3-0ubuntu6
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.3-0ubuntu2b2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.1.0-0ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.21.6-0ubuntu4.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.7-0ubuntu1
xserver.bootTime: Thu Aug 22 22:24:15 2013
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.13.3-0ubuntu6
xserver.video_driver: intel