Window larger than screen

[hipo_loco]

Sorry if my english isn't understood (I'm from Uruguay).

On some computers, if I maximize a window, its size is larger than screen (video: https://www.youtube.com/watch?v=NX10vYe-J_U). A workaround is to change the monitor resolution/frequency after system starts, but if lightdm is restarted it returns.

The problem appears after update lightdm (1.2.3-0ubuntu2.5). With previous version (1.2.1-0ubuntu1) error doesn't happen.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: lightdm 1.2.3-0ubuntu2.5
ProcVersionSignature: Ubuntu 3.2.0-77.112-generic 3.2.66
Uname: Linux 3.2.0-77-generic i686
ApportVersion: 2.0.1-0ubuntu17.8
Architecture: i386
Date: Wed Feb 25 15:26:53 2015
InstallationMedia: Lubuntu 12.04 "Precise Pangolin" - Release i386 (20120423)
MarkForUpload: True
ProcEnviron:
 LANGUAGE=es_UY:es
 TERM=xterm
 PATH=(custom, no user)
 LANG=es_UY.UTF-8
 SHELL=/bin/bash
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)