[Feature]: Support using the "Fn" key alone as push-to-talk hotkey on macOS #1083

Area

Voice capture / hotkey

Problem or workflow

On MacBook Pro (and other MacBook models), the physical keyboard has no "Right Control" key — only a left Control key. The current default hotkey shown in settings is "Right ^" (Right Control), which cannot be pressed at all on the built-in keyboard.

I tried setting the hotkey to "Fn" instead (as some alternative dictation tools support), but the hotkey recorder does not detect the Fn key press at all — nothing happens when Fn is pressed in the recording field.

This is likely because Fn triggers a flagsChanged event on macOS rather than a standard keyDown event, and the hardware sits on a different HID usage page (0x00FF, Apple vendor top-case keys) than regular keys, which the current CGEventTap-based hotkey recorder does not capture.

Proposed Solution

Add a dedicated "Use Fn key" option (similar to a toggle, separate from the normal hotkey recorder) that listens for Fn via flagsChanged events at the .cghidEventTap level, consistent with how other Mac dictation tools have implemented this (e.g. OpenTypeless shipped Fn support in v1.1.49 via the native hotkey path).

Alternatives Considered

Currently working around this by using Right Option (⌥) as the hotkey instead, since it's a real key on the built-in keyboard. This works but is less convenient for one-handed triggering compared to Fn.

Additional Context

• macOS version: MacOS 26.6.2 (25G83)
• OpenLess version: Version 1.3.18 (1.3.18)
• Hardware: MacBook Pro

Before submitting

• I have searched existing issues and discussions.
• I am willing to help test this feature if it lands.