Thanks for this additional information. I just tried to reproduce it and was not able to.
To reproduced I ran "gksuexec" and selected userB and the "id" command. The passwort dialog came up asking me for my password and after that "id" showed the output for userB.
Do you have a explicit root password set? Instead of using your passwort and do everything through sudo (which is the default)?
Thanks for this additional information. I just tried to reproduce it and was not able to.
To reproduced I ran "gksuexec" and selected userB and the "id" command. The passwort dialog came up asking me for my password and after that "id" showed the output for userB.
Do you have a explicit root password set? Instead of using your passwort and do everything through sudo (which is the default)?
Thanks,
Michael