Comment 29 for bug 1409166

After some more research, attempting to use VGA+DP+LVDS is not a valid configuration. The X230 is missing something (TMDS?) to allow this, even though the chipset allows it.

X should have a handler for this. If I manually attach the extra display(s) after logging in, it will restore my config of 2 external displays and disable the LVDS/internal screen. Attempting to add/re-enable the LVDS as a 3rd in this configuration fails, but this is due to the hardware, and it would be nicer to get an explanatory error message rather than:

"Failed to apply configuration: %s
   Can't add monitor: GDBus.Error:org.gtk.GDBus.UnmappedGError.Quark._gnome_2drr_2derror_2dquark.Code2: could not set the configuration for CRTC 65"

So the issue seems to be 1) allowing you to attempt something which isn't valid, and then giving a not very helpful error message, and 2) it's not able to catch/trap the error condition of 3 displays attached prior to attempting to start X, and realising that it can only use 2, which stops X from starting.

Knowing that the configuration of VGA+DP+LVDS is not valid may not be something that can be detected, other than by identifying that the model is an X230 and contains the Intel HD graphics, and not the NVIDIA graphics (which does include the TMDS or other hardware to enable this config to work).

(Apparently the way to be able to continue using the internal LVDS display along with 2 external displays is to not use the VGA port, which requires that you use the DP on the laptop, and with the laptop in a docking/station port replicator, have the second external screen attached via DP on the dock. A 4th screen/3rd external can also apparently be added with the use of the USB based port replicator, which contains another display adapter).