I am nesting a JPanel inside a JTabbedPane. I am having trouble displaying all the content inside of the JTabbedPane. The outside borders of the internal content get chopped off.

I am currently not using a Layout Manager for my JTabbedPane or dummy Panel because it stretches my content automatically.

How do I add a JPanel inside the JTabbedPane so that I can have an even border around all the content.My attempts to create a dummy panel and setting a border for the inner panel using BorderFactory haven't worked. Is there a convention that I need to know to do this correctly?

   JTabbedPane tabPane = new JTabbedPane();
    GridPane tab1 = new GridPane();
    GridPane tab2 = new GridPane();

    tabPane.add("My Pieces",tab1);
    tabPane.add("Opponent Pieces",tab2);

public class GridPane extends JPanel {
    public GridPane()
        {
            this.setPreferredSize(new Dimension(400,160));
            this.setLayout(new GridLayout(4,10));
            this.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
            for (int i = 0; i < 4; i++) {
                for (int j = 0; j < 10; j++) {

                    boardSquares[i][j] = new JPanel();
                    boardSquaresArr.add(boardSquares[i][j]);
                    this.add(boardSquares[i][j]);
                }
            }

        }
}