public MainWindow() { initComponents(); bp = new BoardPanel(mainBoard.getSize(), this); javax.swing.GroupLayout mainBoardLayout = new javax.swing.GroupLayout(bp); bp.setLayout(mainBoardLayout); mainBoard.setLayout(new GridLayout(1, 1)); mainBoard.add(bp); // bp.setPreferredSize(mainBoard.getSize()); mainBoard.repaint(); // }