I dont mind the 2 windows, infact I prefer it even though i'm playing at 720p on a 15" laptop screen O.o.

If for example chat was just in a different tab you would have to switch tabs to check what people are saying whereas with 2 windows the chat can always be infront of you, then the battle spam in another.

I do however like the idea of more than 2 tabs for different classes so it eliminates the need to constantly swap filters every time you change classes.

And the one click maximize is a brilliant idea, when someone answers a question just as people decide to spam chat and its impossible to scroll up to see the answer.