[gentoo-user] X11 recovery ... somehow

Hi,

I am running X11 with Nvidia-drivers 396.18-r1.

From time to time I accidentally hit a key combo
(ALT F*) and I am thrown to the LINUX console.

Back in the years when one setups X11 by hand
carefully inserting timings for the Cathod Ray Tube
it was possible to swicth back with CTRL-ALT-F12 
(or was it ALT-F12).

But this does not work for me.

1) For debugging purposes I would like to 
   get a fully working switch between the
   Linux console and X11 back and forth.
2) If that is not possible see below.

But!
If I was accidentally thrown to the Linux console
by my own eloborated usage of the keyboard (hrrrrmmmm)
I am able to do the following:

Login as myself (console login) and do another
startx.
This will start a new X11 session. 

Is it possible somehow to "take over" the original 
X11 session, which is still running in the background
to cleanly ending the tasks running and waiting for
my input?

Thanks a lot in advance for any help!

Cheers
Meino