When I toggle between full screen mode and window mode (Alt Enter), the "focus" always shifts to the chat window.
This requires me to hit Esc or click out of the chat window each time I toggle modes (e.g., to check e-mail while waiting for party members who are afk).
I can't count how many times I've ended up typing typing "wwwwwwwwww" into general chat because I wanted to move but was focused on chat instead.
If this could be fixed without too much time or risk of causing other problems, it would be a nice UI improvement IMO.