Remember that scala can use the java classes? :) I would start by exploring the Swing framework , which is a Java framework that contains everything you need to get you started creating GUIs. For animation, see javax.swing.Timerwhich triggers events in the event dispatch thread (the thread on which all Swing GUIs should run) - Swing is not thread safe).
Scala , swing- scala.swing, API, Scala swing API 2.7.5
Java Swing, appframework.
, :)