Comment 43 for bug 1615734

Here is my current method of getting multi-monitor setup working, regardless of the monitor type or connection (Thinkpad P50, Ubuntu 16.04.6, driver 384.30):

Initial setup:
--------------
1. Connect your external monitors to your docking station and to electric power, while your Ubuntu desktop is in *locked* screen (or "switch user"). This is important to avoid screen corruption!
1. Edit ~/.config/monitors.xml *manually* to get the exact configuration you want.
2. Save a copy of monitors.xml in case it gets later changed by auto-detection.
3. Connect each of your external monitors to a *switched* power socket - so that you can turn off your monitor completely without disconnecting it from the docking station. NOTE: If the monitor is powered but soft-off (using the monitor's power button), it will still communicate with card, so using the switched socket, you make sure it is completely off.
4. Add to your desktop startup apps the command "/usr/bin/xset -dpms". This makes sure that when screens are darkened after locking, they don't use DPMS, which is faulty and breaks the multi-monitor setup. Instead, software is used to darken the screen, with mouse cursor still visible.

Docking:
--------
1. Switch off the power supply of all the external monitors, using the power socket switch.
2. Dock your laptop, resume operation, still in *locked screeen* - it now runs stand-alone.
3. Flip on the power switch of the external monitors.
4. If all goes ok, your setup will resume correctly - you will see displays being extended or replicated as set in your monitors.xml . Then you can log in and continue work.
5. Sometimes, setup will not resume correctly on first flip. No worries. Just turn off the switch again, wait a few seconds and try again. In my experience, I don't need to do this more than 3 times, and those are rare occasions. If it doesn't work on the 3rd attempt

Un-docking:
-----------
1. Suspend your laptop
2. Undock.

As a general rule: when you connect your laptop to a new external display (e.g., in a meeting room, preparing to project), ALWAYS lock your desktop first before connecting. From my experience, this guarantees much better display stability and smooth user experience. Do expect that when connecting a new display, the net setup will be somewhat arbitrary - whether extending your current display or replicating it. However, this is still easily manageable e.g., when projecting.