How do I cause standalone X11 apps to use MacPorts X11?

[Ludwig]

On Wed, 26 Mar 2014, Kevin Reid wrote:

> The dialog does not come from the application but from the system-provided
> X11.app (this is observable by Dock/menu bar) which is a nonfunctional stub
> (this is what my research says).
> 
> It sounds like the assumption is that when you install third-party X11 as
> instructed by the dialog, it will _replace_ the system-provided X11. But
> MacPorts doesn't replace system files as a rule -- I'm looking for a solution
> which fits into MacPorts's way of working.
>

What happens if you launch these apps from an xterm within MacPorts’ X11?