@Kovid,
I just recognize the old version had not worked for me too and I had forgot to report that some when in May. I just see the remark in my script
I run your new modification from source. It is a bit better as I can now pass a backup directory, but if I select only one of the libraries no library will be backup.
I have a little additional request. Is it possible to add some arguments for scripting? I like to pass a backup directory and in addition only dedicated libraries or "all" as parameters. No parameter means the original behavior as it is now. This would be very helpful.