The following steps are needed to enable dock-connected monitors.

1. Enable the experimental GL driver - Eric Anholt's vc4. You need to run $ sudo raspi-config. Then choose Advanced Options, GL Driver, and finally Full KMS (recommended) or Fake KMS.
   
2. Reboot.
   
3. Install libncurses and dkms: $ sudo apt-get install dkms libncurses5-dev 
   
4. Get the kernel headers using rpi-source: $ sudo wget https://raw.githubusercontent.com/notro/rpi-source/master/rpi-source -O /usr/bin/rpi-source && sudo chmod +x /usr/bin/rpi-source && /usr/bin/rpi-source -q --tag-update ; rpi-source --skip-gcc 
   
5. Execute the .run installer.
   
6. install xserver-xorg-core-hwe version 2:1.19.6-1ubuntu1~16.04.1 (if not upgraded before): $ sudo apt-get install xserver-xorg-core-hwe-16.04=2:1.19.6-1ubuntu1~16.04.1
   
7. Reboot.
   
8. Screen should be added automatically shortly after booting up. 

Known Issues

• DisplayLink driver is confirmed to operate properly with only a specific Xorg and kernel version installed, i.e. xserver-xorg-core-hwe-16.04 version 2:1.19.6-1ubuntu4~16.04.1 and kernel 4.4.38-v7+ were tested. Other versions are not guaranteed to work.
  
• Total resolution limit (all screens) is 2048x2048 and cannot be exceed neither vertically nor horizontally.
  
• In case resolution limit is reached, please use display settings, xrandr or similar tool to set resolution and enable the screen manually. With the default window manager's settings, the notification popup appears when trying to exceed the aforementioned value while auto-adding the screen.