Also, I can't get the window around the Workbench screen to permanently disappear, even though I select the menu option Workbench -> Backdrop and de-select it. I've done this and then done a snapshot of the Windows and icons.
Click into an empty area of the desktop, then select Workbench -> Backdrop from the menu, then select Window -> Snapshot -> Window from the menu. (Do not activate another window inbetween).
You don't need to snapshot icons.
Make sure that envarc:sys/wbconfig.prefs either does not exist or is write enabled.