Solution Ubuntu 16.04.2

[IvanS]

Thanks sandra1n
The solution you described worked for me.
I'm on Xubuntu 17.04 on Thinkpad T450 and using ThinkPad Pro DisplayLink port replicator.
After installing the DisplayLink driver as per instruction, all I've got on external monitors was black screen with mouse moving.
After applying the workaround from post above, both monitors work.

Hardware:
Lenovo ThinkPad T450
DELL 23' - connected via DisplayPort to dock.
SAMSUNG 22' SyncMaster B2240 - connected via DVI to dock.
Lenovo ThinkPad USB 3.0 Pro dock.

Software:
Xubuntu 17.04