How to Apply Insert key action for all opened Documents

Question

I want to apply Insert key Action(Available in keyboard as "Insert" key) for all the opened Documents.By default It didn't work for any document.I write the code for Insert key.But,In my program Insert key Action has worked for only recent opened file only.I want add this feature to all opened files.Please check it once.

Main Class:

public class InsertDemo extends javax.swing.JFrame {
JScrollPane scrollPane;
JTextArea textArea;
public InsertDemo() {
initComponents();
}
@SuppressWarnings("unchecked")                         
private void initComponents() {
tabbedPane = new javax.swing.JTabbedPane();
jMenuBar1 = new javax.swing.JMenuBar();
file = new javax.swing.JMenu();
newFile = new javax.swing.JMenuItem();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
file.setText("File");
newFile.setText("NewFile");
newFile.addActionListener(new java.awt.event.ActionListener() {
    public void actionPerformed(java.awt.event.ActionEvent evt) {
            newFileActionPerformed(evt);
    }
});
file.add(newFile);
jMenuBar1.add(file);
setJMenuBar(jMenuBar1);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
    layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
    .addGap(0, 400, Short.MAX_VALUE)
    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(tabbedPane, javax.swing.GroupLayout.DEFAULT_SIZE, 400, Short.MAX_VALUE))
);
layout.setVerticalGroup(
    layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
    .addGap(0, 279, Short.MAX_VALUE)
    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(tabbedPane, javax.swing.GroupLayout.DEFAULT_SIZE, 279, Short.MAX_VALUE))
);

pack();
}// </editor-fold>                        

private void newFileActionPerformed(java.awt.event.ActionEvent evt) {                                        
textArea=new CaretTextArea();
scrollPane=new JScrollPane(textArea);
tabbedPane.add(scrollPane);
}                                       
public static void main(String args[]) {
try {
    for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
        if ("Nimbus".equals(info.getName())) {
            javax.swing.UIManager.setLookAndFeel(info.getClassName());
            break;
        }
    }
} catch (ClassNotFoundException ex) {
    java.util.logging.Logger.getLogger(InsertDemo.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
    java.util.logging.Logger.getLogger(InsertDemo.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
    java.util.logging.Logger.getLogger(InsertDemo.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
    java.util.logging.Logger.getLogger(InsertDemo.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}

java.awt.EventQueue.invokeLater(new Runnable() {
    public void run() {
        new InsertDemo().setVisible(true);
    }
});
}                
private javax.swing.JMenu file;
private javax.swing.JMenuBar jMenuBar1;
private javax.swing.JMenuItem newFile;
private javax.swing.JTabbedPane tabbedPane;
}

Insert Action class.I create the JtextArea reference through this class.This is extended class of JTextArea.

public class CaretTextArea extends JTextArea {
private boolean isInsertMode=false;
Color oldCaretColor;
Color insertCaretColor=new Color(254, 254, 254);
public CaretTextArea() {
    MyCaret c=new MyCaret();
    c.setBlinkRate(getCaret().getBlinkRate());
    setCaret(c);
    oldCaretColor=getCaretColor();
    addCaretListener(new CaretListener() {
        @Override
        public void caretUpdate(CaretEvent e){
            if (isInsertMode()) {
                processCaretWidth();
            }
        }
    });

    Keymap kMap=this.getKeymap();
    Action a=new AbstractAction() {
        @Override
        public void actionPerformed(ActionEvent e) {
            setInsertMode(!isInsertMode());
        }

    };
    kMap.addActionForKeyStroke(KeyStroke.getKeyStroke(KeyEvent.VK_INSERT,0),a);
}

public boolean isInsertMode() {
    return isInsertMode;
}

public void setInsertMode(boolean insertMode) {
    isInsertMode = insertMode;
    processMode();
}

private void processMode() {
    if (isInsertMode()) {
        processCaretWidth();
        setCaretColor(insertCaretColor);
    }

    else {
        setCaretColor(oldCaretColor);
        putClientProperty("caretWidth", 1);
    }
}

private void processCaretWidth() {
    try {
        int pos=getCaretPosition();
        Rectangle rPos=modelToView(pos)!=null ? modelToView(pos).getBounds() :new Rectangle();
        int caretX=rPos.x;
        int caretEndX=rPos.x;
        if (pos<getDocument().getLength()) {
            Rectangle rNextPos=modelToView(pos+1)!=null ? modelToView(pos+1).getBounds(): new Rectangle();

            if (rPos.y==rNextPos.y) {
                caretEndX=rNextPos.x;
            }
        }
        putClientProperty("caretWidth", Math.max(1, caretEndX-caretX+1));
    } catch (BadLocationException e) {
       // e.printStackTrace();
    }
}

@Override
public void replaceSelection(String content) {
    if (isEditable() && isInsertMode() && getSelectionStart()==getSelectionEnd()) {
        int pos=getCaretPosition();
        int lastPos=Math.min(getDocument().getLength(), pos+content.length());
        select(pos, lastPos);
    }
    super.replaceSelection(content);
}

class MyCaret extends DefaultCaret {

    public void paint(Graphics g) {
        if (isInsertMode()) {
            //we should shift to half width because of DefaultCaret rendering algorithm

            AffineTransform old=((Graphics2D)g).getTransform();
            int w=(Integer)getClientProperty("caretWidth");
            g.setXORMode(Color.black);
            g.translate(w/2,0);
            super.paint(g);
            ((Graphics2D)g).setTransform(old);
        }
        else {
            super.paint(g);
        }

    }
    protected synchronized void damage(Rectangle r) {
        if (isInsertMode()) {
            if (r != null) {
                int damageWidth = (Integer)getClientProperty("caretWidth");
                x = r.x - 4 - (damageWidth/2 );
                y = r.y;
                width = 9 + 3*damageWidth/2;
                height = r.height;
                repaint();
            }
        }
        else {
            super.damage(r);
        }
    }
  }
}