baloon notifications are queued up and may end up being displayed ages later

[Teo]

OBSERVED

When an application generates a baloon notification message (I don't know how they are called, toasts? those which appear within a rounded rectangle on the upper right corner of the screen just below notification area) and another previous one is still visible, the new one is queued and displayed later, and if in the mean time another message is generated, it is queued even further, and so on. They ALL are displayed, one after another, each one taking its full time, and you may end up accumulating a ridiculous amount of baloons that will be displayed when nobody even remembers what generated them.

For example, VLC player generates a toast message each time it loops. I was playing a very short looped video for a few minutes. All the baloons have queued up and now, half an hour after having even closed VLC player, baloons generated half an hour ago are still showing up, one after another; addistionally they are preventing new baloons to be displayed (e.g. new messages in thunderbird) as they will be displayed as soon as the accumulated ones are over.

EXPECTED
When a baloon is generated and a previous one is still visible, one of two behaviours would be reasonable:
A. kill the message being currently displayed and immediately display the new one, or
B. immediately display the new one and shift the old one(s) downwards (the same as skype does, and practically all programs that have been displaying this kind of messages much before Ubuntu supported them at the OS level)

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: unity 5.12-0ubuntu1.1
ProcVersionSignature: Ubuntu 3.2.0-26.41-generic 3.2.19
Uname: Linux 3.2.0-26-generic i686
NonfreeKernelModules: nvidia
.proc.driver.nvidia.gpus.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86 Kernel Module 295.40 Thu Apr 5 21:28:09 PDT 2012
 GCC version: gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
.tmp.unity.support.test.0:

ApportVersion: 2.0.1-0ubuntu9
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,decor,vpswitch,mousepoll,compiztoolbox,snap,place,resize,session,regex,grid,wall,move,gnomecompat,imgpng,animation,fade,unitymtgrabhandles,workarounds,scale,expo,ezoom,unityshell]
CompositorRunning: compiz
Date: Tue Jun 19 19:10:51 2012
DistUpgraded: 2012-05-17 16:45:23,028 DEBUG enabling apt cron job
DistroCodename: precise
DistroVariant: ubuntu
GraphicsCard:
 NVIDIA Corporation G84 [GeForce 9500M GS] [10de:0405] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. Device [1043:15d2]
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
JockeyStatus:
 xorg:nvidia_current - NVIDIA accelerated graphics driver (Proprietary, Enabled, In use)
 pkg:sl-modem-daemon - Software modem (Proprietary, Disabled, Not in use)
 xorg:nvidia_current_updates - NVIDIA accelerated graphics driver (post-release updates) (Proprietary, Disabled, Not in use)
MachineType: ASUSTeK Computer Inc. M51Sn
ProcEnviron:
 TERM=xterm
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-26-generic root=UUID=173acbf5-26a0-49e3-8d2b-f1c142582cbf ro quiet splash
SourcePackage: unity
UpgradeStatus: Upgraded to precise on 2012-05-17 (33 days ago)
dmi.bios.date: 12/24/2007
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 303
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: M51Sn
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: ATN12345678901234567
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr303:bd12/24/2007:svnASUSTeKComputerInc.:pnM51Sn:pvr1.0:rvnASUSTeKComputerInc.:rnM51Sn:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.name: M51Sn
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.
version.compiz: compiz 1:0.9.7.8-0ubuntu1
version.libdrm2: libdrm2 2.4.32-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 8.0.2-0ubuntu3.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 8.0.2-0ubuntu3.1
version.nvidia-graphics-drivers: nvidia-graphics-drivers N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.11.4-0ubuntu10.2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.0-0ubuntu1.2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20111219.aacbd629-0ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.17.0-1ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20111201+b5534a1-1build2