I wasnt saying dont use JavaFX, JavaFX is still great, just HTML 5 came along around the same time as JavaFX and so companies prefer to use that for many use cases. Swing had a lot more time to get entrenched. JavaFX is a much more enjoyable experience than Swing or HTML from a developers point of view, the api and ease of use for developing applications makes it really fun and easy to work with.
IB TWS is written in Java right. Is its latest version using JavaFX? How does it produce those price charts?