There is an application I need to run as root on my Linode server, but it has to run in a gui.

I have ssh and X11 forwarding set up between my Ubuntu 14.04 system and my Linode (swordfish). It works just great for a non-root user (xcalc, xconsole, the application I need to run, etc). However, when I try to run the application on the server as root, I get the error message "X11 connection rejected because of wrong authentication." For xcalc running as root, I get

X11 connection rejected because of wrong authentication.

Error: Can't open display: swordfish:10.0

I have tried all sorts of google solutions - copying the user's .Xauthority to /root/ (also changing the ownership and permissions). But I just can't seem to log into swordfish as a normal user using ssh -X, su to root, and get the X11 forwarding to work.

I also went so far as to install vnc4server on the Linode, xfce window manager, and vnc4viewer on my Ubuntu machine. That all works when I access the vnc server as a normal user, but I can't get any X11 apps to run as root (ie from a root command line in a terminal in the vnc window). The error message when I try to run xcalc or other X11 apps is "No protocol specified. Can't open display :1".

What are the special Linux guru magical incantations/spells to make X11 forwarding work for root?

Thanks!

Mark