These comments relate to Java 6 Update 1 and Update 2 but may apply to
earlier versions (including Java 5) as well.

I am trying to set the height of a table's header by using the following
(very simple) code:

table.getTableHeader().setPreferredSize(new
Dimension(getTableHeader().getWidth(), 22));

This works in that the table header height is set accordingly but there is a
very nasty side effect.  That is, if the table is set up to scroll
horizontally, the header and the body of the table seem to move somewhat
independently. Specifically, if you scroll to the right it will at first
seem that the header has scrolled accordingly but then after a few seconds
delay the header goes back to the start position as though no scrolling had
happened. Nasty.

Can anyone think of a reason why this is happening? Is there a
better/simpler way to set the height of the header in a table that is
configured to scroll horizontally?

Here's a very simple test app that illustrates the problem. Just run it and
scroll to to the right to observe the problem. Why does setting the table
header height lead to such problems? What is the correct way to set the
height of the table header?

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;

public class TableHeaderTest extends JFrame
{
private JTable table;
private JScrollPane pane;

public TableHeaderTest() {
 Object[][] data = new Object[][] {{1, 2, 3, 4, 5, 6},
                                         {2, 2, 3, 4, 5, 6},
                                         {3, 2, 3, 4, 5, 6},
                                         {4, 2, 3, 4, 5, 6}};
 String[] colNames = new String[] {"Column A", "Column B", "Column C",
         "Column D", "Column E", "Column F"};
 setLayout(new BorderLayout());
 pane = new JScrollPane();
 table = new JTable(data, colNames);
 table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
 table.getTableHeader().setPreferredSize(new Dimension(pane.getWidth(),
24));
 pane.setViewportView(table);
 add(pane, BorderLayout.CENTER);
 pack();
 setPreferredSize(new Dimension(280, 250));
 setSize(new Dimension(280, 250));
 setLocationRelativeTo(null);
 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public static void main(String[] args) {
 EventQueue.invokeLater(new Runnable() {
  public void run() {
   new TableHeaderTest().setVisible(true);
  }
 });
}
}