mapping modifier keys swaps left and right

Number:rdar://39961709 Date Originated:2018-05-04
Status:closed Resolved:
Product:macOS + SDK Product Version:10.13.4
Classification:UI Reproducible:yes


In "Keyboard -> Modifier Keys", when mapping Option to Command, left option is mapped to right command, right option to left command.
Similar for mapping Command to Option.

Can cause problems for example when remotely accessing an OS that has a notion of "AltGr" (right alt on international keyboards) for composing accented characters etc.

When mapping Caps Lock to Control, Caps Lock is mapped to Right Control.

Steps to Reproduce:

In System Preferences -> Keyboard -> Modifier Keys, swap "Option" and "Command", set action for "Caps Lock" to "Control"

You can verify results using for example ; this page shows details of key events as seen by the browser, including leftness and rightness.

Expected Results:

Left Command <-> Left Option
Right Command <-> Right Option
Caps Lock -> Left Control (arguably)

Actual Results:

Left Command <-> Right Option
Right Command <-> Left Option
Caps Lock -> Right Control


edit ~/Library/Preferences/ByHost/, correct the key mappings as given by TN2450, log out, log in.


10.13.1, 10.13.4. 

10.12 didn't seem to have this issue.


Looks like it was fixed in macOS Ventura

still broken on 10.14, even after unswapping and reswapping command and option.

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