Testing `ResizableCardLayout` proposed as an answer to https://stackoverflow.com/questions/50184994/cardlayout-in-java-gui - but which doesn't do anything that `CardLayout` doesn't already do

Test.java

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

	public Test() {
		EventQueue.invokeLater(new Runnable() {
			@Override
			public void run() {
				try {
					UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
				} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
					ex.printStackTrace();
				}

				JFrame frame = new JFrame("Testing");
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//				ResizableCardLayout cardLayout = new ResizableCardLayout(frame::pack);
				CardLayout cardLayout = new CardLayout();
				JPanel base = new JPanel(cardLayout);
				base.add(makePanel(200, 200, Color.RED), "red");
				base.add(makePanel(400, 400, Color.BLUE), "blue");

				frame.add(base);
				
				JButton blue = new JButton("Blue");
				blue.addActionListener(new ActionListener() {
					@Override
					public void actionPerformed(ActionEvent e) {
						cardLayout.show(base, "blue");
//						cardLayout.showAndResize(base, "blue");
					}
				});
				JButton red = new JButton("red");
				red.addActionListener(new ActionListener() {
					@Override
					public void actionPerformed(ActionEvent e) {
						cardLayout.show(base, "red");
//						cardLayout.showAndResize(base, "red");
					}
				});
				
				JPanel buttons = new JPanel();
				buttons.add(red);
				buttons.add(blue);
				
				frame.add(buttons, BorderLayout.SOUTH);
				
				frame.pack();
				frame.setLocationRelativeTo(null);
				frame.setVisible(true);
			}
		});
	}

	public TestPane makePanel(int width, int height, Color background) {
		TestPane pane = new TestPane();
		pane.setPreferredSize(new Dimension(width, height));
		pane.setBackground(background);
		return pane;
	}

	public class TestPane extends JPanel {

		private JLabel label;

		public TestPane() {
			label = new JLabel("...");
			setLayout(new GridBagLayout());
			add(label);
		}

		@Override
		public void invalidate() {
			super.invalidate();
			label.setText(getWidth() + "x" + getHeight());
		}

	}

	class ResizableCardLayout extends CardLayout {

		private final Runnable resize;

		public ResizableCardLayout(Runnable resize) {
			this.resize = resize;
		}

		public void showAndResize(Container deck, String cardName) {
			show(deck, cardName);
			resize.run();
		}
	}

}