It created a lightweight viewport, moves the chat down to the lower-left corner and adds a (stylish) border to the chat.
It resizes after the chat.
You might need a lightweight viewport that always keeps behind your chatbox.
You found that you wanted a nice sleek border for your UI, and like it to have a custom or classcolored bored to go with it.
Works out of the box, but if you want something changed, you only need very-little-to-none knowledge of lua, theres only a simple true/false switch for you (the end-user) to toggle.
I've noticed that the chat moves a bit when you lose control of your character and it can look a bit weird. Everything will be back in order when combat ends though.