WindowBlind skin not stretching horizontally fully on resize

If WindowBlinds is launched on my laptop (Win7 x64), 1440 - 900 screen, and then I plug in my external HDMI monitor (1920 x 1080), there is a gap in the texture  (only see this with the SD skins) in the middle of app windows. As the app window is resized (smaller than about 90% (guesstimate) of screen size) horizontally, the gap closes up.

This also happens if I set the resolution of my HDMI monitor to 1440 x 900, restart WindowBlinds and then change resolution back to 1920 x 1080 (only did this for testing purposes)

If I go to "Configure WindowBlinds" and re-select the skin, the "gap" is gone.

See screenshots of gap (3 separate shots in one image)

This appears to happen with all apps, it looks like a resizing issue. I can see where the two images mirror each other where they come together in the center. It's like the skin image/texture hasn't been resized/enlarged enough taking into account the full width of the new resolution.

System:
OS Win 7 x64

WindowBlinds:
Your computer has a Windows Experience Index base score of 4.8
Your Windows Graphics Experience score is 4.9

WindowBlinds version : WindowBlinds 7.42 (325 - Windows 7 Edition) - 64 bit OS

WindowBlinds is installed correctly on this PC
WindowBlinds appears to be activated on this PC
(Dell U2312HM DVI) 1 is attached to NVIDIA GeForce 9600M GT

Wblind.dll         2012/07/13 13:23:20
Wblind64.dll         2012/07/13 13:24:18
Wbsrv.dll         2011/09/26 15:10:56
SevenConfig.exe         2012/07/09 17:44:31
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

Thanks,
Tim