sometimes modal dialogs are not displayed

[Constantine Peresypkin]

Sometimes (actually quite frequently) clicking on items that should display modal dialogs (edit connection, connection information, configure VPN, etc.) are not displayed, at all.
The problem manifests itself only in a dual monitor setup (doesn't matter in which orientation).
monitors.xml attached.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: network-manager 0.9.8.8-0ubuntu7
ProcVersionSignature: Ubuntu 3.13.0-45.74-generic 3.13.11-ckt13
Uname: Linux 3.13.0-45-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.6
Architecture: amd64
CurrentDesktop: Unity
Date: Wed Feb 4 15:55:48 2015
IfupdownConfig:
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2014-01-28 (372 days ago)
InstallationMedia: Ubuntu 12.04.3 LTS "Precise Pangolin" - Release amd64 (20130820.1)
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
SourcePackage: network-manager
UpgradeStatus: Upgraded to trusty on 2014-09-07 (150 days ago)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH
 94:CE:2C:41:8A:46 bluetooth disconnected /org/freedesktop/NetworkManager/Devices/3
 wlan0 802-11-wireless connected /org/freedesktop/NetworkManager/Devices/1
 eth0 802-3-ethernet unavailable /org/freedesktop/NetworkManager/Devices/0
nmcli-nm:
 RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
 running 0.9.8.8 connected enabled enabled enabled enabled disabled