Seems you aren't limited to connecting the virtual out to the virtual in.
Seems you can connect the virtual out to the REAL IN.
See attached.
Oh, and the two bottom link nodes are connected, horizontally only.
Be warned!
It really messes up the flow.
Pressing either A or B, there is the initial display in the respective A or B debug node.
But then it screams which ever button you pressed down the debug list on the right until you get this: "RangeError: Maximum call stack size exceeded"
If you press A or B
See next picture.
Anyway, that aside there is also a problem with how NR deals with the link.
When I select it and delete it, the DEPLOY button doesn't activate.
See next two pictures.
Hmm, makes me think that it would be useful to have something - a script maybe - that outputs the installed and latest versions of Node.js, npm, node-red and packages listed in ~/.node-red/package.json (or more accurately <userDir>/package.json).
I have since found a later command which I had documented.
(Yeah, my filing system needs an overhaul)
I now use: sudo npm install -g --unsafe-perm node-red
Though I am .... a bit weary of it as I have been through the motions of sudo.... before.
And it kind of doesn't say if it needs to be run from the home or node-red directory.
I have been caught out many times on that and was told it has to be the .node-red directory.