Thunar in Fedora 18 and Fedora Rawhide.

[David]

In Fedora 18 when opening the Terminal and becoming 'root' running
Thunar from the CL opens Thunar with a warning that 'you' are running it
as 'root'.

In Fedora Rawhide (to be Fedora 19) when opening the Terminal and
becoming 'root' running Thunar from the CL fails with a message "thunar:
cannot open display:"

What has been changed and how to change it back?
-- 

  David