Buttons sometimes don't get events

Hello,

I have strange problem.
There is split pane in my application.
I added my own event listeners to both
touch buttons -- after that there are oryginal
listeners which do all work and my listeners
which enable or distable left button.
The purpose of my code was to be possible
to show/hide bottom panel and never hide
top panel.

But (I am not sure that it is only situation) when
I play fast with one touch buttons, sometimes
my listeners don't get event! Oryginal listeners
get event because they always show/hide panel,
but my listeners don't -- so sometimes one touch
buttons do nothing after click. Please, play for a moment
with these buttons and you will see.

Please, help me to solve this problem.

Regards,
Robbo

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.plaf.basic.*;

public class Swing5 {
    public static void main(String[] args) {
        new Swing5();
    }

    public Swing5() {
        JFrame f = new JFrame("Swing5");
        f.setSize(300, 100);
        Container c = f.getContentPane();
        c.setLayout(new BorderLayout());
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel p1 = new JPanel();
        p1.setPreferredSize(new Dimension(300, 100));

        JPanel p2 = new JPanel();
        p2.setMinimumSize(new Dimension(0, 50));
        p2.setMaximumSize(new Dimension(0, 50));
        p2.setPreferredSize(new Dimension(300, 50));

        JSplitPane sp1 = new JSplitPane();
        sp1.setDividerSize(15);
        sp1.setOrientation(javax.swing.JSplitPane.VERTICAL_SPLIT);
        sp1.setResizeWeight(1.0);
        sp1.setOneTouchExpandable(true);
        sp1.setTopComponent(p1);
        sp1.setBottomComponent(p2);

        sp1.setUI(new BasicSplitPaneUI() {
            public BasicSplitPaneDivider createDefaultDivider() {
                return new BasicSplitPaneDivider(this) {
                    boolean isSmallPanelOpened = true;

                    public void setBasicSplitPaneUI(BasicSplitPaneUI newUI)
{
                        super.setBasicSplitPaneUI(newUI);

                        splitPane.removePropertyChangeListener(this);
                        if (mouseHandler != null) {
                            splitPane.removeMouseListener(mouseHandler);
                            splitPane.removeMouseMotionListener(mouseHandler);
                            removeMouseListener(mouseHandler);
                            removeMouseMotionListener(mouseHandler);
                        }
                        setCursor(java.awt.Cursor.getPredefinedCursor(
                                            java.awt.Cursor.DEFAULT_CURSOR));

                        if (leftButton.isEnabled() == false)
                            return;

                        leftButton.setEnabled(false);

                        leftButton.addMouseListener(new MouseAdapter() {
                            public void mouseClicked(MouseEvent e) {
                                System.out.println("left");
                                if (!leftButton.isEnabled())
                                    return;
                                leftButton.setEnabled(false);
                            }
                        });

                        rightButton.addMouseListener(new MouseAdapter() {
                            public void mouseClicked(MouseEvent e) {
                                System.out.println("right");
                                leftButton.setEnabled(true);
                            }
                        });
                    }
                };
            }
        });

        c.add(sp1);
        f.pack();
        f.setVisible(true);
    }
}