Asked and answered for Ubuntu 10.10, but I can't get this to work for Ubuntu 11.10. The search domain is not editable when the "Method" is "Automatic (DHCP)". Changing the method results in a removal of all nameserver entries from resolv.conf.
Is this really as broken as it seems, or just poorly documented?
=== After upgrade to Ubuntu 12, followed this link:
http://askubuntu.com/questions/135629/how-to-add-some-additional-dns-search-domains-without-ignoring-the-ones-returned which says to add
append " x.y.org"; to /etc/dhcp/dhclient.conf.