I wasn't acquainted, and the id command reveals more than expected:
pi@raspberrypi:/home/bob $ sudo id pi uid=1000(pi) gid=1000(pi) groups=1000(pi),3(sys),4(adm),20(dialout),24(cdrom),27(sudo),29(audio),44(video),46(plugdev),60(games),100(users),101(input),108(netdev),999(spi),998(i2c),997(gpio),115(lpadmin) pi@raspberrypi:/home/bob $ sudo id bob uid=1001(bob) gid=1001(bob) groups=1001(bob) pi@raspberrypi:/home/bob $
It's not obvious which memberships are required to use the GUI. Nor, alas, is it obvious that group memberships alone are sufficient.
Thank you very much!
bob prohaska