Eli Zaretskii <eliz@gnu.org> writes:

[...]

> Thanks, but I wonder whether a better way would be to modify
> dired-desktop-save-p such that it handled correctly non-string values
> of desktop-files-not-to-save?  That would make the handling of this
> variable more local, which is better for maintenance, I think.
>
> WDYT?

Sure.  Good idea.  Here is a new version.
-- 
Manuel Giraud