Hi there,
just a pointer - there is one scala module (no longer officially maintained, but heavily in use) that needs to be made compatible with the new collections API of Scala 2.13. I created a ticket here: https://github.com/scala/scala-swing/issues/84
So if you feel competent to contribute to that effort (ideally a PR, but also just sketching out what refactoring will be necessary), it will be very much appreciated.
Best, …h.h…