I really like the new UI, but there is one small change that could be done to make it significantly better

I really do. It makes more sense from a usability standpoint. Timestamps on all messages, an easily accessible reaction button, no more seemingly random line breaks between messages. I am a fan of the message highlight as well, although it seems that isn't a popular opinion. Given that hovering over channels, users, and servers have always had a mouse-over effect, I see no problem with this (even more subtle) effect.

That being said, I highly suggest adding customization options. Not everyone likes these, and you there is an appearance tab in the settings. Use it. Put options for us.

One change I highly suggest would be to grayscale the emojis on the quick reaction bar until they are moused over, exactly like the emoji button in the send message box. You already have this feature, so use it- it'll considerably reduce the visual distraction caused by the colorful emojis on the far side of the screen, which move around quickly when there is mouse movement.

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