[FR] Add the ability to customize the repeat rate for repeatfn per hotkey

[NightMachinery]

I like some of my hotkeys to repeat fast, and some slow. I believe there needs to be two settings exposed: the initial delay to start the repeat timer, and the delay between each repeat.

Related:

• Option to customise key repeat rate. #1216
• Slow repeat rate: hs.eventtap.event.newKeyEvent #1211

[cmsj]

I don't think we can really address this unfortunately - the repeat information comes from the default macOS setting for key repeats. We'd have to completely change to using EventTap for all hotkeys, which is not something I think we want to do.