In an active chat room, on the desktop chat client, hovering the mouse pointer over a message puts a lightweight line around that message. Furthermore, if that message a reply to another, or if there are replies to that message, the other messages in the reply chain are highlighted (with a dark background) as well.
In chat transcripts, the thin-line-on-this-message highlighting takes place, but the darker-related-messages highlighting does not. This makes it harder to follow a conversation in the transcript of a crowded room than it is in the room itself --- to the extent that sometimes I will from the chat transcript to the chat room and select "load older messages" an unreasonable number of times to make sure that I understand who was talking to whom.
Is the different treatment of these displays an intentional choice? Could the related-messages highlighting be enabled in the transcript as well? A client-side userscript would be okay, but I use enough different computers that I would prefer something on the server side.
This similar feature doesn't seem to exist for me, and seems like it might have some problematic characteristics if it did.