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If you feel up to it you can edit the .msstyle with a resource hacker and edit the image making it transparent.
I would suggest that you would start a new custom theme so you do not corrupt the original look at Post #38
Here it will show you how(that is Windows 7 but it would be the same way in Windows 8)
This would be creating a custom theme then and you would have to do the following:
Download UxStyle_Core For Windows 8 and later operating systems
UxStyle
Turn off UAC
http://www.eightforums.com/tutorials/5509-user-account-control-uac-change-settings-windows-8-a.html reboot, install UxStyle reboot.
To give you the correct image numbers I will need you to go to C:\Windows\Resources\Themes\Aero folder and get a copy of the aero.msstyles and put it in a zip folder and post it here.
If it seems too hard I could do it for you and post it here.
Let me know.
Jerry