Context: I installed an app called "Scroll Reverser" which will allow me to use the natural scrolling setting for my trackpad and the opposite scrolling setting for my mouse scroll wheel. The application requires the Privacy permission "Input Monitoring". The description of this is to "Allow the apps to monitor input from your keyboard even while using other apps".

So does Apple just consider mouse inputs, like scrolling, an "input from your keyboard"?

The app was recommended by another user on this site: How to separate "mouse" and "trackpad" settings?

  • Just a heads up I've edited your question to remove the "If so, is there any way to allow an application to invert my scrolling for my mouse (without changing trackpad scrolling) without also granting them permission to monitor input from my keyboard)?" part . That's really a different question and, if there's not already an answer on this site, feel free to ask it again as a separate question.
    – Monomeeth
    Aug 23, 2019 at 23:44

1 Answer 1


Scrolling can be a keyboard input. For example, using the arrow keys on a keyboard will often scroll the window.

While I have no experience with the Scroll Reverser app, a quick check shows the source code is available. And, according to its Read Me file:

Scroll Reverser installs an event tap, which gives access to event stream, including scrolling events and gesture events. The main documentation is Quartz Event Services Reference.

To distinguish between trackpad and mouse, Scroll Reverser essentially looks at the gesture events to determine whether there are 2 or more fingers on the trackpad. If so, it assumes it is the trackpad.

Since the app uses Quartz Event Services then it's basically monitoring low level inputs from users. More technical information is available on the Quartz Event Services page on Apple's Developer site.

But essentially, monitoring low level inputs also means monitoring keyboard inputs.

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