Some observations: Calling someList.observable() ...
# tornadofx
Some observations: Calling someList.observable() will create an observable list backed by the underlying list, but mutations on the underlying list will not emit events. You should instead initialize actors as an observable list right away. Access to an observable list must happen on the UI thread, so you need to wrap mutation calls in runLater. For people trying to run your example - you didn't include a stylesheet, but references one in your App subclass, so the IDEA will most probably import the TornadoFX Stylesheet class. This will not end well 🙂 The also call has no effect, so I removed it. I updated your code to best practices here and there, for example with regards to how to create the root node 🙂