OK...
So your changes in shell32.exe are only about the grid setup.
I'll certainly combine that with the transparency trick, then.
CPRs often contain a "Background" tag. These are the most commonly found :
portrait :
Code:
<Image ID="Background" Left="0" Top="-52" Visible="True" Opacity="1.0" ScalingAlgorithm = "TriLinear" Source=".\StartMenu_Background_Screen_480x800.png"/>
Landscape :
Code:
<Image ID="Background" Left="0" Top="-27" Visible="True" Opacity="1.0" ScalingAlgorithm = "TriLinear" Source=".\StartMenu_Background_Screen_800x480.png"/>
Notice the "Top" value, most probably responsible for the offset problems I've been battling against in order to try aligning Sense and Start menu wallpapers... It's even obviously calculated for WM6.5, though it was found in a WM6.5.3 ROM !
Without the tag at all, only stwater_480_800.jpg and stwater_800_480.jpg are showing under the icons, and they are kind enough to cover the screen without an offset.

---------- Post added at 09:37 AM ---------- Previous post was at 09:11 AM ----------
Excuse me, while I'm thinking about it...
I've been modifying shell32.exe and aygshell.dll files for a long time, and always been working from original files extracted from the exact ROM I was using.
I've then noticed they were always different for each build.
And now, I'm using the shell32.exe you provided and it works straight out of copying to the \Windows folder, without even worrying for compatibility.
So why are there so many differences, while it obviously doesn't matter so much ?
And from what build was your shell32.exe originally extracted, please ?