Feature Request: Layout Protection with "Linked Keyboard and Mouse" Displays

[airforceixi]

Mac allows you to link your keyboard and mouse with neighboring Mac systems. However BetterDisplay will change the anchor points between the two systems quite often as it applies other protections/locks and I'm required to adjust the arrangement. Is it possible to add a way to lock these anchor points, similar to current display groups?

[waydabber]

Sadly API does not provide (afaik) any way to query and configure Universal Control (the "link keyboard and mouse to") feature. There are of course undocumented/private APIs that control this feature, but by looking at the UniversalControl (and Ensemble?) framework I did not find anything useful (I see some control procedures, there are XPC call possibilities obviously and some connections to the usual Skylight framework - with clear indications that interacting with any of these require special Apple-given entitlements + there is a related configuration file com.apple.universalcontrol.(UUID).plist that probably saves the state as well in a kind of binary blob - with some work its structure might be understandable, but it would only help maybe reading the current configuration or where a remote device should end up once connected, not to manipulate it). By nature this feature involves multiple Apple devices.

So even though I tagged this as an "enhancement", it is highly doubtful that this can be implemented - unless of course Apple decides to give developers some control over this (which is very doubtful, Apple is really hesitant to give useful APIs to anything hardware or display related nowadays, most of the much more basic stuff can only be reached by reverse engineering undocumented stuff, most actually documented APIs are mostly outdated and semi-functioning right now and come from an earlier age of macOS development when Apple still pursued a more open approach).

[waydabber]

Related: #5824