TestHOMainFrame.java

import com.github.weisj.darklaf.DarkLaf;
import com.github.weisj.darklaf.LafManager;
import com.github.weisj.darklaf.theme.DarculaTheme;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

public class TestHOMainFrame extends JFrame {

    public static void main(String[] args) {
        TestHOMainFrame frame = new TestHOMainFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        try {
            LafManager.setTheme(new DarculaTheme());
            UIManager.setLookAndFeel(DarkLaf.class.getCanonicalName());
            SwingUtilities.updateComponentTreeUI(frame);
        } catch (Exception e) {
            e.printStackTrace();
        }

//        HOTabbedPane tabbedPane = new HOTabbedPane();
        JTabbedPane tabbedPane = new JTabbedPane();

        for (int i = 0; i < 5; i++) {
            tabbedPane.addTab("Tab " + (i+1), new JPanel());
            tabbedPane.setPreferredSize(new Dimension(600, 400));
        }

        frame.getContentPane().add(tabbedPane);
        frame.setTitle("Example of HOTabbedPane");
        frame.pack();

        SwingUtilities.invokeLater(() -> frame.setVisible(true));
    }    
}