The setting to change brightness and volume at the same time for all displays doesn't work. This happens both with the keyboard shortcut and the menu bar widget, they only do one display at a time. (version 1.2)
Hi again @Amir-Hass ,
Thank you for testing this, as I currently don't have a multi-monitor setup I couldn't test it well. I'll try to see if I can find another monitor to squash this bug soon.
Have a nice day !
I confirm it doesn't work, changing brightness/contrast with sliders works fine, for external monitor but doesn't work for internal display.
Hi @funbben ,
Actually, this was not what I had in mind with this option. MonitorControl doesn't handle at all the internal display, so the settings should only affect (in theory since I haven't tested it) external display for now.
But as it's a very good suggestion I'll had this to the list of things to do. (Maybe as a separate setting for example)
I would love to be able to control internal+external brightness together.
@the0neyouseek Maybe you could use code from Brightness Menulet to achieve this.
Brightness Menulet sets the brightness for the internal screen as well.
One thing thats really convenient, is the option to follow the main screens (internal screens) brightness, which dims/brightens the external display automatically with the internal display, when the ambient light sensor of the iMac/MacBook detects changes there.
@cseelus: Your excellent idea is being explored here: #27.
The idea of controlling the internal monitor along with the external is great. It has some caveats, though:
So, a locking solution needs to consider this, and yes, it will be absolutely worth the pain to do so. This is an excellent feature.
I would also gladly have the same locking solution for the volume. The same caveats apply to the volume level.
Hi, @retrography , thanks for getting back

I can't say much about the volume settings though, as I only use Headphones (via TB3-Dock) or a pair of Speakers via Bluetooth.
Well I had tried the Brightness Menulet because of this, and it's Follow Main Screen option works great for me, but the app has a bug that only one of my two identical monitors gets controlled, and it's apparently not supported anymore. So yeah.. It's a shame there still isn't one DDC app which has everything working.
I'm working on this in #148, I'm going to try to make it respect the "Change brightness/volume for all displays" checkbox and allow the user to select it from the display preferences.
Not 100% sure how well it would work since talking to the internal display requires the usage of another (private) api, the same one other brightness tools use. Tracking progress mostly in there.
Most helpful comment
Hi @funbben ,
Actually, this was not what I had in mind with this option. MonitorControl doesn't handle at all the internal display, so the settings should only affect (in theory since I haven't tested it) external display for now.
But as it's a very good suggestion I'll had this to the list of things to do. (Maybe as a separate setting for example)