Can you help me with some short code like how to resize a Toolbar when the maximize button is pressed..
I'll do better.  Here's a short code sample that shows 5 of them with different resize behavior depending on where they are placed in a BorderLayout.

import java.awt.BorderLayout;
import javax.swing.*;
public class ResizableToolBars {
    public static void showFrameWithToolBar(String toolBarPosition) {
        // the layout is important..
        JPanel gui = new JPanel(new BorderLayout());
        JToolBar tb = new JToolBar();
        // ..the constraint is also important
        gui.add(tb, toolBarPosition);
        tb.add(new JButton("Button 1"));
        tb.add(new JButton("Button 2"));
        tb.addSeparator();
        tb.add(new JButton("Button 3"));
        tb.add(new JCheckBox("Check 1", true));
        JFrame f = new JFrame(toolBarPosition + " Sreeeetchable Tool Bar");
        f.setContentPane(gui);
        f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        f.setLocationByPlatform(true);
        f.pack();
        // we don't normally set a size, this is to show where 
        // extra space is assigned.
        f.setSize(400,120);
        f.setVisible(true);
    }
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable(){
            @Override
            public void run() {
                showFrameWithToolBar(BorderLayout.PAGE_START);
                showFrameWithToolBar(BorderLayout.PAGE_END);
                showFrameWithToolBar(BorderLayout.LINE_START);
                showFrameWithToolBar(BorderLayout.LINE_END);
                showFrameWithToolBar(BorderLayout.CENTER);
            }
        });
    }
}
If you come back to the Nested Layout Example after that, you should be able to figure out how I put it together from smaller groups of components, each in their own layout (in a panel) in one area of a parent container.
