I've reduced my problem to a short, self-contained example,
below.  I have a JFrame that has a JSplitPane, that has a
JTree (left) and JTextArea (right).  I can't get resize
behavior to work correctly.  I've tried many combinations of
setting minimum size & preferred size on each/all of the
components, but nothing did what I wanted.  Here's a minimal
example:

import java.awt.*;
import javax.swing.*;

public class SplitPaneDemo extends JFrame {
 public SplitPaneDemo() {
   super("Split Pane Demo");

   Container container = getContentPane();
   JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT);
   splitPane.setLeftComponent(new JTree());

   JTextArea textArea = new JTextArea();
   splitPane.setRightComponent(textArea);
   textArea.setLineWrap(true);

   container.add(splitPane, BorderLayout.CENTER);

   setDefaultCloseOperation(EXIT_ON_CLOSE);
   setSize(500, 500);
   setVisible(true);
 }

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

If I dont setLineWrap(true) then I can move the JSplitPane's
separator bar correctly.  As it is here, I can move it left,
but not right.  It seems like the JTextArea is resizable
bigger, but not smaller, when LineWrap is true.

My actual program is a lot more involved (the right hand side
is a JTextArea in a JPanel (along with other components) on
a JTabbedField on the right hand side of the JSplitPane), but
I'm obviously missing something basic.  What's the CORRECT
way to get the above working correctly?

Thanks.