Can I remove the 'carrot' (upside down triangle) created by the ComboBoxListViewSkin?

Question

When implementing the java ComboBoxListViewSkin class to manage the popup listener of my ComboBox, this adds a 'carrot' to the upper left corner of the ComboBox (see below). If I remove this class implementation it goes away. I'm using the CombBoxListViewSkin's class popup listener to prevent the [SPACE] from selecting and closing the ComboBox when pressed which allows the [SPACE] character to be typed as part of an AutoComplete class.

This is all the code involved in managing and allowing the [SPACE] to work as part of AutoComplete class -and works great. I've tried searching the ComboBoxListViewSkin class for methods or properties that may prevent this, but nothing addresses this. I thought maybe the COMBO_BOX_STYLE_CLASS might offer something but everything really only manages the displaying, adding or removing items. Since the code below is the minimal necessary to recreate the issue, this will not perform the auto-complete function, but it demonstrates that removing and re-implementing the ComboBoxListViewSkin class causes the issue.... or appears to.

// Main method calling

public class Main extends Application{

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

    public void start(Stage stage) throws Exception {

        ComboBox cmb = new ComboBox();
        cmb.getItems().setAll("One", "One Two", "One Two Three");
        new ComboBoxAutoComplete(cmb);
        Scene scene = new Scene(new StackPane(cmb));
        stage.setScene(scene);
        stage.setTitle("Test GUI");
        stage.setWidth(300);
        stage.setHeight(300);
        stage.show();
    }
}


// ComboBoxAutoComplete class with ComboBoxListViewSkin initialization
// Minimal of ComboBoxAutoComplete class constructor

import com.sun.javafx.scene.control.skin.ComboBoxListViewSkin;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.control.ComboBox;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;

import java.util.stream.Stream;

@SuppressWarnings("ALL")
public class ComboBoxAutoComplete<T> {

    private ComboBox<T> cmb;
    private String filter = "";
    private ObservableList<T> originalItems;

    private ComboBoxListViewSkin cbSkin;

    public ComboBoxAutoComplete(final ComboBox<T> cmb) {
        this.cmb = cmb;
        originalItems = FXCollections.observableArrayList(cmb.getItems());

        cbSkin = new ComboBoxListViewSkin(cmb);

// Aside from the variable declaration and initialization... this 
// is the only ComboBoxListViewSkin code to handle the [SPACE]

        cbSkin.getPopupContent().addEventFilter(KeyEvent.KEY_PRESSED, (event) -> {
            if (event.getCode() == KeyCode.SPACE) {
                filter += " ";
                event.consume();
            }
        });
    }
}

My expectation is for the ComboBox to look like all the other ComboBoxes in the application GUI. Although it is a minor issue, to the user I believe it may look like an issue with the application is going on.

Answer 1

Resolved: As Fabian suggested above, I added a cmb.setSkin(cbSkin) after the initialization and before the event filtering and it worked. Thought I would post so others would see it was resolved.

    cbSkin = new ComboBoxListViewSkin(cmb);
    cmb.setSkin(cbSkin);   // <-------------  ADDED

    cbSkin.getPopupContent().addEventFilter(KeyEvent.KEY_PRESSED, (event) -> {
        if (event.getCode() == KeyCode.SPACE) {
            filter += " ";
            event.consume();
        }
    });