After a bit of research I've found that C:\windows\web\wallpapers should
be the location for wallpaper selection when you try to edit your
desktop. Per the registry entry for 'wallpaperdir'. But for the life
of me, I also get 'my pictures' images showing up in the selection.

I store my pictures in 'my pictures'. Who would guess! And I really
don't want them as wallpapers.

Am I missing something? Is there a way to force Windows to pick from
just the specified folder only?