How can I create two dimensional SplitPane in Java Swing
<p>I want to create a two dimensional <code>JSplitpane</code> like design in Java swing.
Such that the <code>JFrame</code> will be split into 4 parts, and upper and lower parts are separated by another split, and left and right part are separated by yet another split line. Also if I click and drag any part of vertical split line, the complete line should move in dragged direction.</p>

<p><a href="https://i.stack.imgur.com/agTOh.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/agTOh.jpg" alt="ScreenShot"></a></p>

<p>I am trying to achieve this, by using split pane within split pane. But then on dragging vertical split line, it only drags either components below horizontal line or above horizontal split line.</p>

<pre><code>import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Demo extends JFrame {

int screenwidth=760,screenheigth=550;

JSplitPane top_sp,bottom_sp,main_sp;

JButton b1,b2,b3,b4,b5,b6;
JButton b7,b8,b9,b10;

MailClient(){
    setSize(screenwidth,screenheigth);
    setLayout(new BorderLayout());
    setTitle("Demo");
    setDefaultCloseOperation(EXIT_ON_CLOSE);    
    setLocationRelativeTo(null);

    b1=new JButton("B1");
    b2=new JButton("B2");
    b3=new JButton("B3");
    b4=new JButton("B4");
    b5=new JButton("B5");
    b6=new JButton("B6");
    b7=new JButton("B7");
    b8=new JButton("B8");
    b9=new JButton("B9");
    b10=new JButton("B10");     

    JPanel topleft=new JPanel(new FlowLayout());
    topleft.add(b1);
    topleft.add(b2);

    JPanel topright=new JPanel(new FlowLayout(FlowLayout.CENTER));
    topright.add(b3);
    topright.add(b4);
    topright.add(b5);
    topright.add(b6);

    JPanel bottomleft=new JPanel(new FlowLayout(FlowLayout.CENTER));

    bottomleft.add(b7);
    bottomleft.add(b8);
    bottomleft.add(b9);
    bottomleft.add(b10);

    JPanel bottomright=new JPanel(new FlowLayout(FlowLayout.CENTER));
    bottomright.add(new JLabel("TABLE"));

    top_sp=new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,true,topleft,topright);
    bottom_sp=new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,true,bottomleft,bottomright);

    main_sp=new JSplitPane(JSplitPane.VERTICAL_SPLIT,true,top_sp,bottom_sp);

    add(main_sp,"Center");

    setVisible(true);
}

public static void main(String args[]){
    Demo demo=new Demo();

}

}
</code></pre>