I have a network manager applet on my xfce4 desktop. I am logged in as a non root user, and I can select edit connections and change the IPv4 settings to DHCP address only and then put in a DNS, then save. If I look at /etc/resolv.conf though nothing has changed. Restarting networking or rebooting makes no difference. Perhaps this menu option should only appear for root, or should cause an error message for non root users?