comment highlight tool (highlighting is visible only to streamers and mods)
unlike most of the other "chat highlighting" ideas/complaints this idea is for a moderator tool
it would be a button available in Moderator Mode alongside the time out and ban buttons next to each comment in the chat.
The purpose of it is to ensure that other mods and the streamer notice that particular chat.
for the average streamer the most common usage of this would be for one mod to warn other mods to watch a particular person in the chat. maybe that person is "testing the water" by making increasingly escalating comments, but has not "crossed the line" yet.
another example of usage would be during a q&a stream, where mods might potentially want to highlight specific questions for the streamer to address. for example on a Deep Astronomy stream, a mother asked a question for her astronomy loving 8yr old child, and Tony the streamer almost didn't notice in spite of my highlighted messages and whispers which he wasn't reading trying to draw his attention to that particular question among the many others... being able to highlight it as a mod would have made it stand out amongst all the other questions for the guest.
as such this type of highlighting should stand out in a way that is different from other forms of highlighting, and maybe having an accompanying list.
chat moves so fast sometimes that there's not time to type something out so being able to just click a button next to a comment could make all the difference.
I've heard of some science communication streamers custom programming a bot to read the chat and create a list of all of the questions. this would be kind of like that but more flexible and targeted in its usage