Please oh please oh please I'm dying to have an experience bar that I can have showing all the time without opening inventory, AND without having a massive player info window.
I'd like a skinny long bar that maybe runs the length of the screen along the bottom under chat? Or along the top? Just the XP bar, nothing fancy. It doesn't necessarily HAVE to run the full width of the window either. Just a little bar I can move around, maybe stretch to desired length?
That is entirely possible, however, it needs to live inside an existing window. You can not add new windows. Some common windows UI developers have used is the target window, potion belt, mp3 player, and even hotbars (although these days that is more of a pain).
You can add it to the chat window, but it will be duplicated in every chat window you create.