Apple Thunderbolt display does not adhere to brightness hardware instructions

[Birowsky]

Regardless what I set through my keyboard brightness buttons, it resets its own brightness after a second.
Here's a demo:

brightness.demo.mp4

Once I quit BetterDisplay, my external keyboard controls the display properly. It does not reset.

[waydabber]

I am sorry, I don't really understand what am I seeing. :) But I see you are running f.lux which will for sure interfere with BetterDisplay (unless color table adjustments are disabled).

[Birowsky]

Here's another attempt at explaining with audio:

Screen.Recording.2024-09-21.at.13.13.54.mp4

This happens even when f.lux is off.

I don't experience this issue with MonitorControl: https://github.com/waydabber/MonitorControl/releases/tag/v4.3.0-beta

[Birowsky]

Has this been received? Should I open an issue?

[waydabber]

Sorry, no, I did not notice the issue.

Honestly I am not sure why that is happening. Clearly something is controlling the display. Based on how the slider works (updates every 1/4 seconds - the exact frequency to what the system brightness change debouncer is configured in the app) it seems like the app is just being informed by the system that the brightness of the display is changing (for whatever, possibly external - to the app - reasons) so the app updates it's own brightness reading and the associated slider - the change itself does not seem to be initiated by the app. Do you see the display dimming meanwhile?

Are sure you are not using any other app or setting that might regulate the external display (based on time of the day for example or some other means?). If you use Control Center to change the external display's brightness or BD is not running do you experience anything similar? I see that you are using quite a bit of various apps/tools.

[waydabber]

(note: I see Lunar installed, it specifically has a feature to change brightness based on time of the day or schedules).

[Birowsky]

Do you see the display dimming meanwhile?

Yes

Are sure you are not using any other app or setting that might regulate the external display (based on time of the day for example or some other means?).

f.lux only influences the yellow tint based on time of day. But the issue persists even with f.lux not running.

If you use Control Center to change the external display's brightness or BD is not running do you experience anything similar?

Nope.

I see Lunar installed, it specifically has a feature to change brightness based on time of the day or schedules

It is installed, but not running. It has different problems.

the change itself does not seem to be initiated by the app

Screen.Recording.2024-09-25.at.14.28.31.mp4

I should point out that I don't experience this issue using MonitorControl, but I'd rather buy a well maintained tool.

[waydabber]

Hmm. Indeed, this is interesting and might be something else. I see that the control center slider moves in the same manner as the BetterDisplay slider, not smoothly.

• Do you have this issue if you adjust the Control Center slider while the app is running bot not using the keyboard?
• If you quickly quit BetterDisplay, does the decrease of brightness continue in the same manner?
• Does this happen if you use the BetterDisplay slider to adjust the brightness?ú
• What if you let the keyboard control only one display's brightness?
• Is there any kind of syncing enabled in BetterDisplay? Or are all app settings are set to default (except as I see the keyboard controlling all screens at once)?

[Birowsky]

Do you have this issue if you adjust the Control Center slider while the app is running bot not using the keyboard?

The problem is there, if i change it here:

There is no problem if I change it here:

If you quickly quit BetterDisplay, does the decrease of brightness continue in the same manner?

I did a manual brightness change to trigger the misbehavior:

• If I immediately force quit BD, the dimming does not start
• If I wait a bit for the dimming to start, and then force quit BD, the dimming proceeds till the end.

Does this happen if you use the BetterDisplay slider to adjust the brightness?

Yes

What if you let the keyboard control only one display's brightness?

Please instruct me how to do this

Is there any kind of syncing enabled in BetterDisplay? Or are all app settings are set to default (except as I see the keyboard controlling all screens at once)?

Since I'm not sure what exactly am I looking for, here's my full configuration

[Birowsky]

An update. Turning this off and on, seems to have fixed the issue:

[waydabber]

Please instruct me how to do this

I was thinking about changing this to the default (first) setting:

This seems to be some kind of hardware control issue but I think this might be some kind of BetterDisplay bug actually in the AppleControl module - just not sure what. :) Turning that off might solve the issue apparently but the app will then fall back to software control which is not as ideal.

Can you try the latest v3.0.6 pre-release version? You should go to Application/Updates and enable pre-release and then internal pre-release and check for updates.

If the issue can be reproduced with that version, I might give you a version that does some logging to see what happens internally.

You say if you quit BetterDisplay right after changing the brightness, the change still happens? You might want to do your timing well - prepare a Terminal window and enter killall BetterDisplay, do the brightness change using the keyboard and then hit enter and see whether the decreasing of brightness still goes through even when the app is killed. I just want to know whether this is something BetterDisplay is doing actively or some other system service that might be specific to Thunderbolt Displays.

Thank you!

[Birowsky]

Well, we have a different problem now. I cannot reproduce the issue since I did this:

What do you suggest? : )

[waydabber]

Hmm. I have no idea lol.

[waydabber]

Let me know if the issue happens again I guess and then we'll move forward debugging it. I'll try to think about it meanwhile what could have gone wrong.

[Birowsky]

👍