Run this test program :

"
import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.scene.Scene;
import javafx.scene.control.MenuButton;
import javafx.scene.control.MenuItem;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

public class TestMenuButton extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        MenuButton button = new MenuButton("button");
        MenuItem item = new MenuItem("this is a test");
        button.getItems().add(item);
        button.setMinSize(500, 500);
        
        BorderPane pane = new BorderPane(button);
        Scene scene = new Scene(pane);
        primaryStage.setScene(scene);
        primaryStage.show();
        
        primaryStage.setHeight(200);
    }
}
"
Click on the menuButton, the MenuItem is displayed out of the main window. In fact it's displayed at the bottom of the menuButton but since the window has a lower height, the menu item appears completely outside.

Is this a normal behavior?