On the Mac, you can hold down the key on certain characters (e and o being the most obvious uses for me) which will cause a menu to appear allowing you to select a special version of that letter (ë or ö for example). See screenshot for preview of menu.

Normally when this keyboard character is held down, no input is provided to the UI until a sub-character is chosen.

Ripcord unfortunately does not seem to follow this pattern, and instead inputs the held key repeatedly before the menu appears.

Expected behavior (if possible) - holding the key should not repeat characters if there is a menu that appears (or perhaps replace the repeated characters once a sub-character is chosen?).

This doesn't happen on my Mac with any program. I've never heard of this feature before.

Could you be more specific or provide more information?

I can confirm that this problem still exists in 0.4.24. See this blog post for more details: https://infinitediaries.net/os-x-choose-between-the-character-accents-popup-and-key-repeat-when-holding-down-a-key/