import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;

import java.util.logging.Level;
import java.util.logging.Logger;

import javax.swing.AbstractAction;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.KeyStroke;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

public class ClipboardHanger
{
    public static void main(String[] args)
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setSize(400, 300);
        f.setLocationRelativeTo(null);

        final WriteDoc doc = new WriteDoc();
        final JEditorPane ta = new JEditorPane();
        ta.setDocument(doc);
        f.setLayout(new BorderLayout());
        f.add(ta);

        String KEY = "KEY";
        ta.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, InputEvent.CTRL_MASK, false), KEY);
        ta.getActionMap().put(KEY, new AbstractAction()
        {

            @Override
            public void actionPerformed(ActionEvent e)
            {
                doc.writeLockPub();
                try
                {
                    for (int i = 0; i < doc.getLength(); i += 10)
                    {
                        doc.insertString(i, "   ", null);
                    }
                }
                catch (BadLocationException f)
                {
                    Logger.getLogger(Logger.GLOBAL_LOGGER_NAME).log(Level.SEVERE, f.getLocalizedMessage(), f);
                }
                finally
                {
                    doc.writeUnlockPub();
                }
            }
        });

        f.setVisible(true);
    }

    static class WriteDoc extends PlainDocument
    {
        public void writeLockPub()
        {
            super.writeLock();
        }

        public void writeUnlockPub()
        {
            super.writeUnlock();
        }
    }
}