jtable/jscrollpane issues

import java.awt.BorderLayout;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;

public class MyFrame extends JFrame{

    private JPanel panel1;
    private JTabbedPane tabs;
    private JButton runButton;

    public MyFrame(){
        tabs = new JTabbedPane();
        panel1 = new JPanel();
        runButton = new JButton("go!");
        runButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                runButtonActionPerformed(evt);
            }
        });
        panel1.add(runButton);
        tabs.addTab("first tab", panel1);
        this.add(tabs);
        pack();
    }

    public static void main(String args[]) {
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                MyFrame frame = new MyFrame();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    private void runButtonActionPerformed(java.awt.event.ActionEvent evt) {
        /* Normally there is more stuff happening here
         * but this much will do for the sake of example
         */
        List<String[]> data = new LinkedList<String[]>();
        for(int i=1; i<1000;i++)
            data.add(new String[]{"entry1", "value1", "value2", "value3"});

        SwingUtilities.invokeLater(new DataPreviewAction(data, tabs));
    }

    public class DataPreviewAction implements Runnable {

        private JTabbedPane contentHolder;
        private List<String[]> data;

        public DataPreviewAction(List<String[]> data, JTabbedPane comp){
            this.contentHolder = comp;
            this.data = data;
        }

        @Override
        public void run() {
            DefaultTableModel previewModel = new DefaultTableModel(){
                @Override
                public boolean isCellEditable(int row, int column){
                    return false;
                }};

            for(String[] datarow : data){
                previewModel.addRow(Arrays.copyOf(datarow, datarow.length, Object[].class));
            }

            JTable table = new JTable(previewModel);

            JPanel buttonPanel = new JPanel();
            buttonPanel.add(new JButton("A button"));
            buttonPanel.add(new JLabel("Some description for the awesome table below "));
            buttonPanel.add(new JButton("another button"));

            JScrollPane tablePanel = new JScrollPane(table);
            JPanel container = new JPanel();
            container.setLayout(new BorderLayout());
            container.add(buttonPanel,BorderLayout.NORTH);
            container.add(tablePanel,BorderLayout.CENTER);
            contentHolder.addTab("Preview", container);
            contentHolder.validate();
            contentHolder.repaint();
        }
    }
}