This is a minor, and 100% cosmetic issue, but the Devil is in the details..

When you add a disabled MenuItem into a ContextMenu, everything is as expected.

When you add a disabled Menu into a ContextMenu, the disabled Menu never appears to receive mouse over events, and a bit confusingly, the MenuItems next to this disabled menu continue to have "mouse over effect", even if the disabled Menu is actually hovered.

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.ContextMenu;
import javafx.scene.control.Label;
import javafx.scene.control.Menu;
import javafx.scene.control.MenuItem;
import javafx.stage.Stage;

public class MenuTest extends Application {
@Override
public void start(Stage stage) throws Exception {
Label root = new Label();

ContextMenu menu = new ContextMenu();

menu.getItems().add(new MenuItem("MenuItem 1"));
menu.getItems().add(new Menu("Menu 1"));
menu.getItems().add(new MenuItem("MenuItem 2"));
menu.getItems().add(new MenuItem("MenuItem 3"));
menu.getItems().add(new MenuItem("MenuItem 4"));

menu.getItems().get(1).setDisable(true);
menu.getItems().get(4).setDisable(true);

root.setContextMenu(menu);

Scene scene = new Scene(root, 400, 400);
stage.setScene(scene);
stage.show();
}

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