After b19 installed the taskbar icons have a strange 'double' edge at the rightside only. There is only one window of Outlook open.

Sorry, didn't see till now and in the latest beta, 21, the shadow is gone.

oops, and there they are again.

Here's the troubleshooting info: http://dl.dropbox.com/u/1828618/displayfusionlog.txt

any, i tried several they all show up like that.

here a screenshot:

The link above to the logfile has been updated with the troubleshoot info at the same time of the screenshot

Tried the group buttons. I click on it, the taskbar reloads, but no change.

I use WindowBlinds.
Your computer has a Windows Experience Index base score of 5.9
Your Windows Graphics Experience score is 7.8

WindowBlinds version : WindowBlinds 7.2 (build 303 - Windows 7 Edition) - 64 bit OS

WindowBlinds is installed correctly on this PC
WindowBlinds appears to be activated on this PC
(LGE E2240 (GSM57A3 EDID Override)) 1 is attached to AMD Radeon HD 6900 Series
(LGE E2240 (GSM57A3 EDID Override)) 2 is attached to AMD Radeon HD 6900 Series

Wblind.dll 2011/03/29 11:34:20
Wblind64.dll 2011/03/29 11:34:15
Wbsrv.dll 2010/08/09 14:03:56
SevenConfig.exe 2011/03/29 11:34:52
Wbload.exe 2010/09/07 23:02:35
Wbhelp.dll 2010/09/07 23:02:34
Tray.dll 2010/04/01 17:44:19
Wbload.dll 2010/04/27 11:10:25
Screen.exe 2010/05/26 17:18:43

you can add it to the WB list

Twiddled a bit with the transparency settings in WB, now the shadow only shows up if one hovers over the button. I'd give this one a miss to solve. Not worth the trouble.