Problem

Shortcuts using option + letter (e.g. option + q) stop working intermittently. option + number works reliably. Re-opening the app's settings window temporarily restores them.

This was reported in a downstream app, FlashSpace, whose author directed me here.

Root Cause

I believe this is a fundamental conflict between Carbon's RegisterEventHotKey and the macOS Input Method Engine (IME).

On macOS, option + letter combos (e.g. option + q → œ) are processed by the Text Services Manager before Carbon hotkey events are dispatched. As a result:

• option + 1 → no character composition → kEventHotKeyPressed fires reliably
• option + q → triggers IME composition (œ) → the event is consumed upstream and never reaches the Carbon event handler

This doesn't always happen — it depends on the active application's IME mode, which is why the issue appears intermittently.

Why the Settings Window "Fixes" It

Looking at HotKey.swift, when a menu is open, HotKeyCenter switches from RegisterEventHotKey to a RunLoopLocalEventMonitor with .eventTracking run loop mode (raw NSEvent key events), which intercepts events before the IME layer. When the window closes, it switches back to RegisterEventHotKey, and the issue returns.

Connection to isDisallowed

I also noticed Shortcut.swift has an isDisallowed check for option + letter on macOS 15.0/15.1 in sandboxed apps — which suggests this is a known Apple regression. However, isDisallowed only affects the RecorderCocoa UI, not the actual hotkey registration, so the shortcut can still be registered but may silently fail to fire.

Question

Is there a way to use RunLoopLocalEventMonitor (or a CGEventTap) permanently for shortcuts that involve option + letter, rather than only when a menu is open? That would allow intercepting events before the IME layer at all times.

Or alternatively, could isDisallowed be broadened to cover more macOS versions or non-sandboxed apps, with a warning shown to users that option + letter shortcuts are unreliable?

Environment

• macOS version: 26.3
• Tested via FlashSpace app