Expanding the topic makes the contents of the chat move

[nougatmachine]

When a user expands the topic area so s/he can read the whole thing, the contents of the chat window are actually scrolled down to make room for the expanded topic. So if I want to still be able to read what was most recently said in a chat window, I either need to de-expand the topic, or I need to scroll back down again. It seems like it would be much more preferable to simply have the topic, when expanded, to cover up the topmost area of the chat window, as opposed to moving the contents of it.

[nougatmachine]

Mockup of a potential interface change for this

[nougatmachine]

In the channel last night, xenon pointed out that the way Colloquy currently arranges its interface means that this ticket can't be easily implemented. I've attached a mockup of a potential solution and would be eager to here thoughts on it from anyone. :)

I think this looks fine visually, but I do worry about the expand button and the scroll bar now being right next to each other. That may be setting up a situation where it's too easy to miss one and get the other.

[nougatmachine]

One potential hangup: what to do with the "expand" button before the scrollbar appears?