To run X11 apps remotely via SSH in a FreeBSD 7.0 jail, I had to do the following things.

• install the xauth port in the jail
• install the xorg-fonts port in the jail
• install the app in the jail
• add "X11Forwarding yes" to /etc/ssh/sshd_config in the jail
• add "X11UseLocalhost no" to /etc/ssh/sshd_config in the jail
• add to /etc/hosts in the jail
• restart sshd in the jail