BlackBerry Forums Support Community - what's wrong with this button?

Why does a single-item "close" menu appear when this button is clicked with the trackwheel but no menu appears when it is "clicked" by pressing ENTER when it has focus? If I add an edit field, the default main menu appears when the trackwheel is clicked in the edit field (which is what I want), but when the button defined below is clicked with the trackwheel that single-item "close" menu appears (which I DON'T want). What am I doing wrong with this button?

Code:

// ----- ButtonTestScreen.java ----------------------------------

package buttontest;



import net.rim.device.api.ui.*;

import net.rim.device.api.ui.component.*;

import net.rim.device.api.ui.container.*;



public class ButtonTestScreen extends MainScreen {

        

    public ButtonTestScreen() { }



    public boolean onClose()

    {

        Dialog.alert("BYE!");

        System.exit(0);

        return true;

    }

    

}

Code:

// ----- ButtonTest.java ----------------------------------

package buttontest;



import net.rim.device.api.ui.*;

import net.rim.device.api.ui.component.*;

import net.rim.device.api.system.*;



public class ButtonTest extends UiApplication implements FieldChangeListener

{

    private boolean clicked;

    private LabelField appTitle;

    private ButtonField testButton;

    private ButtonTestScreen mainScreen;

    

    public static void main(String[] args)

    {

        ButtonTest app = new ButtonTest();

        app.enterEventDispatcher();

    }

    

    public ButtonTest()

    {

        clicked = false;

        ButtonTestScreen mainScreen = new ButtonTestScreen();

        appTitle = new LabelField("Button Test");     

        testButton = new ButtonField("Click Me");   

        testButton.setChangeListener(this);           

        mainScreen.setTitle(appTitle);

        mainScreen.add(testButton);

        pushScreen(mainScreen);

    }



    public void fieldChanged(Field field, int context)

    {

        if (field == testButton)

        {

            if(clicked)

            {

                clicked = false;

                testButton.setLabel("Click Me"); 

            }

            else

            {

                clicked = true;

                testButton.setLabel("Clicked");

            }

        }

    }    

    

}