Title bar becomes inactive when window is unmaximised

[Jacek Nykis]

I noticed a problem affecting some programs under 13.04

How to reproduce:
* open a window, for example file manager
* drag the window to the top of the screen so that it is maximised
* drag the window back to the desktop to un-maximise it

Expected:
* windows works as usual, title bar buttons active and window can be moved

Observed:
* window cannot be moved by dragging title bar (but Alt+ mouse drag still works)
* close, minimize and maximize buttons do not work, clicking on them has no effect
* some of the title bar functionality is still there. If I change focus to another window and then click on the affected window's title bar focus changes however buttons still do not work and the window cannot be moved.

This affects most of the applications but not all of them. So far I noticed the problem in:
firefox, nautilus, thunderbird, rhytmbox and software center

The probme does NOT affect:
gnome-terminal

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: unity 6.12.0daily13.03.20-0ubuntu1
ProcVersionSignature: Ubuntu 3.8.0-13.23-generic 3.8.3
Uname: Linux 3.8.0-13-generic x86_64
ApportVersion: 2.9.2-0ubuntu2
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Thu Mar 21 11:50:44 2013
InstallationDate: Installed on 2013-01-19 (61 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
MarkForUpload: True
SourcePackage: unity
UpgradeStatus: Upgraded to raring on 2013-03-19 (1 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.