JSplitPane, JScrollPane, JPanel & resize

Question

My program has 2 nested JSplitpanes, that divide the screen in 4 parts like a cross.
I added a JScrollPane to one of the quaters and added a JPanel to the JScrollPane. The JPanel uses a CardLayout since I want to switch the components that I show there.
One of the components I show on the JPanel is a JTree. If I expand the tree the panel becomes scrollable to show the whole tree. This is what I want because I want to be able to view the whole tree.
The problem is, that if I switch to another component on the panel the panel stays that large even though I just want it to have the visible size
This is how the panel looks like before switching to the tree and expanding it:
http://img272.imageshack.us/img272/8695/noscroll3zj.jpg
This is how the panel looks like after switching to the tree, expanding it and switching back:
http://img272.imageshack.us/img272/6690/scroll3ef.jpg
I want to restore the panel to its initial state but I cannot figure out how. Please help.

Answer 1

If I add a panel to the split pane (to make it card layout) I can't use it for scrolling anymoreThis simple example works for me:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class SplitPaneCard extends JFrame
     JSplitPane splitPane;
     JPanel cards;
     public SplitPaneCard()
          splitPane = new JSplitPane();
          getContentPane().add(splitPane, BorderLayout.CENTER);
          JTextArea textArea1 = new JTextArea(5, 10);
          textArea1.setText("1\n2\n3\n4\n5\n6\n7");
          textArea1.setForeground( Color.RED );
          JScrollPane scrollPane1 = new JScrollPane( textArea1 );
          JTextArea textArea2 = new JTextArea(5, 10);
          textArea2.setText("1234567");
          textArea2.setForeground( Color.BLUE );
          JScrollPane scrollPane2 = new JScrollPane( textArea2 );
        cards = new JPanel( new CardLayout() );
        cards.add(scrollPane1, "red");
        cards.add(scrollPane2, "blue");
        splitPane.setRightComponent( cards );
          JPanel buttonPanel = new JPanel();
          getContentPane().add(buttonPanel, BorderLayout.SOUTH);
          JButton red = new JButton("Show Red Text Area");
          red.addActionListener( new ActionListener()
               public void actionPerformed(ActionEvent e)
                  CardLayout cl = (CardLayout)(cards.getLayout());
                  cl.show(cards, "red");
          buttonPanel.add(red);
          JButton blue = new JButton("Show Blue Text Area");
          blue.addActionListener( new ActionListener()
               public void actionPerformed(ActionEvent e)
                  CardLayout cl = (CardLayout)(cards.getLayout());
                  cl.show(cards, "blue");
          buttonPanel.add(blue);
     public static void main(String[] args)
          final SplitPaneCard frame = new SplitPaneCard();
          frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
          frame.pack();
          frame.setLocationRelativeTo( null );
          frame.setVisible(true);
}