build: M0
NB: 6.0

Steps to reproduce:
  - Create a JavaFX application
  - Copy the following code to the JavaFX editor
    ------------------------------------------------
    import javafx.ui.*;
        import java.lang.System;

        Frame {
            title:   "JavaFX"
            width: 400
            height: 90
            content: Button{
                text : "Click Me"
                action: operation(){
                    System.out.println("Hello World!");
                    }
                }
                visible : true
            }
    ------------------------------------------------
  - Enable the preview
  - Press 'Click Me' button on the preview panel
    The "Hello World!" message is not printed