Using Multi-head and VNC with XFce

[peter_r]

Hello everybody,

currently I'm using a setup consisting of two Lenovo ThinkPads (x230 + x220) both running Gentoo and each connected to the local network. To control the x220 with same keyboard and mouse, I use Synergy server or client respectively. The x230 also has an external display attached, and using xrandr my Xfce desktop is spanned over both screens. While the x220 is never removed from my desktop, the x230 may also be used as mobile device, so the network connection to x220 as well as the external display are not always available. I've written some simple scripts to execute xrandr and to control the xfce panel in both scenarios. So far so good, everything works fine...

Now I wondered, if it would be possible to use the x220 as a full third screen e.g. by using a VNC viewer and displaying a virtual, remote display from x230. Of course, the display should be integrated into the "large desktop" which is already spanned over the notebook-screen and the external one. I think, that a possible solution could be to use x11-drivers/xf86-video-dummy +xinerama in conjunction with x11-misc/x11vnc. But currently, I really have no clue on how to setup this, especially how to extend the desktop from local/attached display to the virtual one displayed remotely.

For better visualization, what I want is the following: Notebook-Display (left, x230) <--> external display (middle, connected to x230) <--> Notebook-Display (right, x220)

Up to now, I do not have a configuration underneath /etc/X11/xorg.conf.d, so everything works "out of the box", and, thus, also in unknown environments (e.g. a beamer for presentation issues).

Is it possible to setup a configuration remotely displaying a virtual XServer, while extending the local Xfce desktop?
What I have to do on both machines to get it to work? Are there any alternatives (I also have taken a look at xdmx, but unfortunately it was really slow...)?

Kind regards,
Peter