[TriLUG] attaching to remote X session (_not_ VNC)

[Kevin Hunter Kesling]

Hello TriLUG,

As a matter of (currently) academic curiosity, does anyone know how to 
attach to an already running remote X session?  Or, put differently, 
since X is oriented around an X server (generally the "desktop"), and 
clients that draw to it (e.g., Firefox, Gimp, Xournal, /any/ GUI 
program), is it possible to redirect (or copy) what the remote X server 
is receiving to a local one?  Or some combination, like redirecting a 
single application to another X server?

Every time I google something like this, I come up with solutions like 
"use VNC" which is not what I want.  I specifically want an X solution 
that dynamically changes or copies where visual output goes and from 
where events are received (like keyboard and mouse).

A potential scenario:

   1. I leave a GUI editor open on a machine while at work.

   2. I go home, and realize I forgot to save some buffers.  I want
      to save those buffers, so that I can continue working where I
      left off tonight.

To put any workarounds out-of-mind, the exercise is to redirect the GUI 
to my now-local X so that I can interact with it -- without 
killing-to-reopen any applications, or opening new instances.  (Perhaps 
this GUI editor does _not_ have scriptable command line interactions 
like "--save-unsaved-buffers".)  Put differently, the application should 
be oblivious to the fact that the image it is sending to X is going 
elsewhere.

Again, I'm specifically curious if this is possible with X alone, rather 
than using a workaround like VNC.  In my academic curiosity, a tool that 
tells the X client to change where it's sending data is fine, so long as 
it's not a service-based workaround like VNC, and does not require being 
run before one realizes they want to connect remotely.

Does this make sense?

Kevin