This happens with other skins too.
LINK: https://www.wincustomize.com/explore/windowblinds/6867/

Your computer has a Windows Experience Index base score of 5.9
Your Windows Graphics Experience score is 7.5
WindowBlinds version : WindowBlinds 7.4 (320 - Windows 7 Edition) - 64 bit OS
WindowBlinds is installed correctly on this PC
WindowBlinds appears to be activated on this PC
(SyncMaster XL2370(Digital)) 1 is attached to AMD Radeon HD 7700 Series
Wblind.dll 2012/04/11 12:31:20
Wblind64.dll 2012/04/11 12:31:05
Wbsrv.dll 2011/09/26 15:10:56
SevenConfig.exe 2012/04/10 18:38:58
Wbload.exe 2010/10/20 16:08:35
Wbhelp.dll 2011/10/04 10:01:37
Tray.dll 2009/10/23 20:12:19
Wbload.dll 2010/06/07 15:59:25
Screen.exe 2010/06/07 15:59:43
I also experience strange shadow in Firefox over the tabs, when Firefox is not in fullscreen. Not in IE though.
