The Swing text components don't handle KEY_TYPED events with the Backspace character; apparently they listen to the corresponding KEY_PRESSED events instead. That is a problem for some Windows input methods, which implement an "Undo Commit" feature by sending WM_CHAR messages with the Backspace character to delete recently committed text. These messages do produce the desired result in AWT text components, as the following test case shows:

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

public class SwingBackspace extends Applet {

    private static TextArea awtTextArea;
    private static JTextArea swingTextArea;

    public void init() {
        setLayout(new GridLayout(2, 1, 10, 10));
        awtTextArea = new TextArea();
        swingTextArea = new JTextArea();
        add(awtTextArea);
        add(swingTextArea);
    }
    
    private void postEvents(Component target, String text) {
        EventQueue queue = Toolkit.getDefaultToolkit().getSystemEventQueue();
        for (int i = 0; i < text.length(); i++) {
            char ch = text.charAt(i);
            queue.postEvent(new KeyEvent(target, KeyEvent.KEY_TYPED, 0, 0, KeyEvent.VK_UNDEFINED, ch));
        }
    }

    public void start() {
        postEvents(awtTextArea, "AWT - hello, bug\u0008\u0008\u0008\u0008\u0008!");
        postEvents(swingTextArea, "Swing - hello, bug\u0008\u0008\u0008\u0008\u0008!");
    }
    
    public void stop() {
    }

    public static void main(String argv[]) {
        SwingBackspace test = new SwingBackspace();
        test.init();
        
        Frame frame = new Frame("SwingBackspace Test");
        frame.pack(); // adds peer
        frame.add("Center", test);
        frame.setSize(400, 400);
        WindowListener listener = new WindowAdapter() {
                public void windowClosing(WindowEvent e) {
                    e.getWindow().dispose();
                    System.exit(0);
                }
            };
        frame.addWindowListener(listener);
        frame.pack();
        frame.show();
        
        swingTextArea.requestFocus();

        test.start();
    }
    
}