Mildly confusing, no biggie: when you leave the world to pop open a new window for skill learning, there's a route at the top back into the world. I expected it to flip me back to my existing browser tab/window, instead it made a fresh one and spent a while re-logging-me-in, eventually invalidating the first window since "I'd logged in elsewhere". Can't you test for an existing game window and re-use it, maybe?
Dan