System Monitor graph fades when enlarging window size beyond a certain size.

System Monitor graph fades when enlarging window size beyond a certain size in Gnome-shell.

I noticed this issue only with ATI cards and when I am using Gnome3 (Gnome-shell).
I also noticed that glxgears report (300fps) substantially lower frame rate per second in gnome-shell as appose to when using unity or gnome classic (8000fps).

The best way to understand the problem is to see the screen shot images that I attach to this bug report.
If I decrease the System Monitor window to almost the minimum, then the graph suddenly become good.
I noticed this problem even when I was using ubuntu 11.10 and now with 12.04.

I am using catalyst 2.14
Driver Packaging version: 8.96.7-120312a-135598C-ATI
2D Driver Version: 8.96.4

My glxinfo reports:
OpenGL vendor string: Advanced Micro Devices, Inc.
OpenGL renderer string: ATI Radeon HD 5700 Series
OpenGL version string: 4.2.11627 Compatibility Profile Context
OpenGL shading language version string: 4.20

this is my uname result:
Asus:~$ uname -a
Linux Asus 3.2.0-26-generic #41-Ubuntu SMP Thu Jun 14 17:49:24 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

$ lsb_release
LSB Version: core-2.0-amd64:core-2.0-noarch:core-3.0-amd64:core-3.0-noarch:core-3.1-amd64:core-3.1-noarch:core-3.2-amd64:core-3.2-noarch:core-4.0-amd64:core-4.0-noarch

$ apt-cache policy gnome-system-monitor
gnome-system-monitor:
  Installed: 3.4.1-0ubuntu1
  Candidate: 3.4.1-0ubuntu1
  Version table:
 *** 3.4.1-0ubuntu1 0
        500 http://mirror.de.leaseweb.net/ubuntu/ precise/main amd64 Packages
        100 /var/lib/dpkg/status

Let me know if you need any further information.
Thanks