I added a group role named
gis to a database using pgAdmin III 1.14.2 using the
Default Privileges tab of the db's properties.
I can confirm it worked because if I click on the db, this shows up at the bottom of its SQL:
ALTER DEFAULT PRIVILEGES
GRANT SELECT ON TABLES
TO gis;
However, if I right-click on the db, go to
Properties, then select the
Default Privileges, it does not show any group roles:

Near the bottom of the pgAdmin Object browser, under Group Roles is this role:
Aren