the program below is to position a jpanel at the top left conner of jframe with gridbaglayout but instead a very small box is displayed in center of jframe. when I set the layout of jframe to null, the jpanel displays fine. can someone tell me why the jpanel is compressed to the center of frame with gridbaglayout? i really need to use gridbag. please help

```
import java.awt.*;
import javax.swing.*; //swing package

public class Major {

    //defining the constructor
    public Major() {
        JFrame maFrame = new JFrame("The main screen"); //creating main Jframe
        JPanel headPanel = new JPanel(); //creating the header panel
        maFrame.setSize(900, 700); //setting size
        maFrame.setBackground(Color.LIGHT_GRAY); //setting color of frame
        Container container = maFrame.getContentPane();
        container.setLayout(new GridBagLayout()); //setting layout of main frame
        GridBagConstraints cns = new GridBagConstraints(); //creating constraint
        cns.gridx = 0;
        cns.gridy = 0;
        maFrame.setLocationRelativeTo(null); //centering frame
        headPanel.setBackground(Color.WHITE);
        headPanel.setSize(200, 150);
        container.add(headPanel, cns);
        maFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //setting the default close operation of JFrame
        maFrame.setVisible(true); //making the frame visible
    }

//defining the main method
    public static void main(String[] args) {
        new Major(); //instantiating the class
    }
}

```