Recent behavior change with DL 4.4 driver [RESOLVED]
 

I've been using a DisplayLink-based Plugable UD-3900 for a while now with version 4.4 of the driver. I use it to connect an HDMI monitor in addition to the one my System76 Kudu can more directly support.

I'm running PopOS 18.10, which is based on Ubuntu 18.10 (Cosmic Cuttlefish).

I try to stay up to date on system software, and I think I remember seeing something related to gdm updating recently, but I'm not confident of that.

After accidentally running a game in full-screen mode, I found I could no longer use both external monitors at once. If only the direct-HDMI monitor was connected, it would work, and if only the UD-3900-to-HDMI monitor was connected, it would work. If both are connected, only the one connected through the UD-3900 works.

This morning, I uninstalled the DisplayLink driver and reinstalled using the 5.1 version that was released on February 19, but haven't seen a change in the behavior from this process.

How can I get this working again?

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Unrelated issue:

When I connect the monitor through the UD-3900, I get mouse-related graphical glitches, such as the cursor disappearing, several copies of the cursor flashing at various previous locations, and other glitches in a square around the mouse cursor.

I did find a AskUbuntu question where restarting the display manager was suggested, and that does resolve it for me until the next reboot, at the cost of closing all my open application windows. (Link: https://askubuntu.com/questions/9473...-nvidia-driver)

Is there a better solution than killing my desktop manager session?

My main issue was quite puzzling, but I eventually found it was due to an OS setting for the displays. In the Displays panel of the PopOS! Settings app (derived from the similar app on Ubuntu, I presume), there's an option to mark displays as disabled.

After finding that, it was a simple matter to mark the display as enabled again, and things seem to be working well again.

For the smaller issue with the mouse artifacts, I'll watch what happens next time I restart and see if it's still an issue for me.

Okay, I think things are working for me the way I want.

The dock does seem to have some stability issues, but they are easy enough to work around when they come up (unplug all the cords, wait a bit, plug them all in).

The only thing that seems a little weird that might be related is that the mouse cursor has a small amount of flicker, and that's easy enough for me to ignore.