What does the indicator icon with three dots over a power plug mean in Ubuntu 20.04?

I have a Dell XPS 15 9570 with a Dell WD19 Dock and on this Dock I have 2 Monitors. The internal Monitor of the Notebook is off but the Lid is open.

I have installed Ubuntu 20.04 LTS.

Everything is working fine, except the following Icon in the Top bar is blinking (Appearing and Disappearing). I don´t know what that is. It looks like a cord but the Notebook charging as expected.

It blinks sometimes in a faster and another Time in a slower speed -> Something between 2 - 5 Seconds.

Appearing:

Disappearing:

The Dock are the complete Time connected.

Exact behavior: It's blinking when I have connected my Laptop to the WD19 Docking Station. It's not blinking when I connect my Laptop ONLY to the normal Power Cord or have NO connection to Dock and Power Cord. But it's also blinking when I connect to the Docking Station AND the normal Power Cord.

Do anyone knows what this means? And how can I stop this? It's really annoying when some icons jumping all the time left and right!

Here I found some logs. Maybe this is the Event:

Solution 1:

The image is known as a cable snake:

From the author's blog:

GNOME Shell

The GNOME shell bits to enable Thunderbolt 3 support were merged some time ago and made it into 3.28. This means that the GNOME shell will act as authorization agent and will automatically authorize new thunderbolt 3 devices — if the user has administrator rights, is currently logged in and the session is unlocked. It will also show a little indicator (called the cable_snake by some) in the status indicator section while devices are being authorized because the whole authorization dance can take quite a while.

Correspondence from developer

I emailed the developer today and this is our conversation:

There are users annoyed with Cable_Snake icon making icons shift left and right in the application indicator top bar. Is there a way to disable the icon but keep boltd running?

This was introduced via a change in the kernel/udev, but a work-around laded in bolt 0.9: https://gitlab.freedesktop.org/bolt/bolt/-/issues/156

There is an ubuntu bug open: https://bugs.launchpad.net/ubuntu/+source/bolt/+bug/1892657

Is there a way to disable the icon but keep boltd running?

Currently not, GNOME Shell is hardwired to react to boltd's probing setting. Best way is to update bolt.

Some ideas of my own

I use the Unity interface where application indicators are right justified on the top bar so new apps opening and closing on the left are preferred and not a disadvantage.

For Gnome Users to prevent icons jumping back and forth the only band-aid I can think of is moving all icons to the right side. This can probably be achieved here:

• How can I order Gnome3 shell extensions at the top?

If this works, then when the boltctl icon appears and disappears on the left side nothing "jumps around".

Solution 2:

Disclaimer - I will post some information even though it's not the solution for the problem but maybe others can pitch in and provide more information to find the solution.

The process causing appearing is boltd/boltctl. As in Dumitru Alexandru Surdu's answer is described you can check what's happening with boltctl monitor. You will message Probing started when icon appears and Probing done when icon disappears. Now, you could disable boltd service but I do not think you would want that since this service manages thunderbolt.

Strictly speaking this is not a bug because icon just shows what's happening in the background but it is very annoying. I guess we can call it UX bug.

If anyone finds a solution or some other information how we can solve it (where to report this kind of problem?), please comment or edit.