As James_D sayd:
ObservableList is just a subinterface of java.util.List, so you can just call all the usual methods: indexOf(...), add(..), remove(...), etc – James_D May 14 at 15:41
Thx, worked fine. As I expected it as first but I messed up my fxml structure and my added fxml did not contain a VBox as root element it contained a Grid. The toString()
from the Grid produces the Grid hgap=0.0, vgap=0.0, alignment=TOP_LEFT
in the output