Looked for a ticket for this, but didn't see it, so I figure it should be filed. Pretty easy to reproduce: enable persistent chat, open the popup and try typing @thought and then make a big 😦 because typeahead doesn't work. You can test it directly on this instance.

This also applies to emojis, new icon typeahead, etc.

I'm guessing that fixing this requires Inception-levels of Javascript programming so you can deeply nest these dynamic popups as much as a user desires.