Don't mind the Game Content (Lighting, Transparency, yay!) but the UI got some upgrades:
The first change is that you can now split your chatbox into multiple ChatFrames which each has it's own ChatChannel Filter (Filter by Category). You also see that they have different Chat Colors (Say is white, Global yellow, Debug blue and Error red).
After taking Paul's Examples I was able to make the box finally fold out into the right direction as you can see on the right box. I've also converted anything into an AppState
The "bug" you see on the left is actually a feature: First we determine how many lines of chat could fit into the given size and so a larger resolution/chat box leads to more lines of text. Additionally we take care of wrapping: Here, the message before was too large to fit into the box and so it's not shown.
I am uncertain whether I should keep that space as is or resize the panel. I disliked having a "jumpy" panel, though so it's fixed. This is part of my lousy scrolling implementation which you don't see:
The ChatMessages are stored in a buffer/list and you only see a part of them (defined by index and said maximumNumberOfLines). This part is then added to the Container/Panel as you can see.
That way I can scroll on a per-element-base at least.
Eventually I could also add filling the free space by the last few words of the previous message, however that would be a sorta costly operation (Checking the height for each additional character done backwards).
This post also clearly shows that I didn't study enough for today, so I'll feel bad now