changing "dual-view" to "mirror-view" with the monitor tool is failing on specific situations

I have a Laptop (A) with an external Monitor (B) and i use them that every device will show its own screen.

When i switch to "mirror view" and the monitor-setting-tool (part of gnome-control-center) is on the extend desktop, it will not be visible after i changed my setup to "mirror-mode". That will result in a switch-back because the monitor-tool is asking if everything is ok, when i do not answer with yes within 15 seconds, the old mode will be used again.

So when switching from "dual-view" to "mirror-view" ALL windows should be merged to the primary screen.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gnome-control-center 1:3.4.2-0ubuntu0.8
ProcVersionSignature: Ubuntu 3.2.0-37.58-generic 3.2.35
Uname: Linux 3.2.0-37-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: amd64
Date: Wed Feb 6 12:38:36 2013
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-control-center
UpgradeStatus: Upgraded to precise on 2013-01-15 (21 days ago)
usr_lib_gnome-control-center:
 activity-log-manager-control-center 0.9.4-0ubuntu3.2
 deja-dup 22.0-0ubuntu2
 gnome-bluetooth 3.2.2-0ubuntu5
 indicator-datetime 0.3.94-0ubuntu2