Hi all,

Attached is a one-liner patch to the “ghost key” problem on NS. (The name is made up by me.) I didn’t have luck finding a bug report (but it did happen to many to-be-liberated Mac users [1-3]), so I decided to directly send it here.

On certain occasions (*), the key event buffer is not cleared to be empty even if the events have been processed. This results in a nasty problem: when you press a key, say “y”, a key that is pressed earlier will be prepended to the current key. There’s no way to reset the event buffer.

This problem is highly unpredictable, making it very hard to reproduce. A probably quicker way: hack Emacs’ C codebase with corfu-auto and citre-mode.

(*) The root cause is still not clear to me. It’s observed that sometimes, the [interpretKeyEvents] call seems not to return. (Blocked inside Cocoa?) And the supposedly matched “remove” is never called. Now “nsEvArray” is left with an earlier keyDown event, and since “nsEvArray” is static, you have the problem as described above. I guess it may be some Cocoa internal changes that caused this.

This patch is just a workaround, but it improves the current user experience a bit.

Regards
Kai

[1] https://emacs-china.org/t/emacs-rime-e/20286
[2] https://emacs-china.org/t/emacs/15430
[3] https://emacs-china.org/t/topic/13207