Creating a ComboBox with an ObservableList as the source does show the contained items in the popup as expected. Opening the popup again after removing an item from the ObservableList shows white spaces at the end of the popup list. The popup doesn't seem to 'shrink' as expected. Possibly related: RT-37622 RT-39030 RT-38731

- Removing an item *before* opening the popup for the first time works as expected.
- setVisibleRowCount() doesn't work after the popup has been opened before.
- Reproduced on (probably not limited to) 8u25 on Windows 7 & Windows 8.1 x64
- Works on OS X Mavericks 8u5, 8u25 & Ubuntu (unknown version) 8u25 as expected.

The following example shows the unexpected behavior (apparently only on Windows systems):


package comboboxquirk;

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 * - ComboBox will be filled with an ObservableList containing 7 Strings
 * - Opening the ComboBox shows the 7 Strings as expected
 * - Clicking the Button once removes the 4. String-item ("Cucumber") from the ObservableList
 * - Expected: The String-item "Cucumber" is removed from the pupup-list, the list only shows the remaining items
 * - Actual: The String-item "Cucumber" HAS been removed, BUT the popup-list shows an additional blank item at the end
 *
 * @author Arjan
 */
public class ComboBoxQuirk extends Application {

    ObservableList<String> demoList;

    @Override
    public void start(Stage primaryStage) {

        // Simple VBox, displaying a ComboBox and a Button
        VBox vbox = new VBox();

        // Setting up the demo list
        demoList = FXCollections.observableArrayList();
        demoList.add("Apple");
        demoList.add("Banana");
        demoList.add("Pineapple");
        demoList.add("Cucumber");
        demoList.add("Coconut");
        demoList.add("Pumpkin");
        demoList.add("Zucchini");

        // ComboBox
        ComboBox<String> comboBox = new ComboBox<>(demoList);
        comboBox.prefWidthProperty().bind(vbox.widthProperty());
        comboBox.maxWidth(Double.MAX_VALUE);

        // Button, removes String "Cucumber" when pressed once (further items, subsequently)
        Button button = new Button("Remove Item");
        button.prefWidthProperty().bind(vbox.widthProperty());
        button.maxWidth(Double.MAX_VALUE);
        button.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                demoList.remove(3);
            }
        });

        Label label = new Label("Notice the content of the ComboBox. Pressing the Button will remove an Item. Now the ComboBox shows strange white blanks.\nWhen removing an item *before* looking at the ComboBox's content, everything's fine.");
        label.setWrapText(true);

        // Add ComboBox and Button to VBox
        vbox.getChildren().addAll(comboBox, button, label);
        vbox.setSpacing(5);

        // Setup scene and display the window
        Scene scene = new Scene(vbox, 350, 150);
        primaryStage.setTitle("ComboBox Quirk");
        primaryStage.setResizable(false);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

}