GUI desinger suspend with custom jpanel

Hello,

I have strange problem with gui designer. When im adding my custom JPanel, IDEA suspend work. There is no errors in terminal. Sometimes its posible to close designer.

public class FigurePanel extends JPanel {
    private static final int rowsNumber = 30;
    private static final Dimension size = new Dimension(10, 10);
    protected static final Color selectionColor = new Color(0x000000);
    private Color originalColor;
    private JPanel grid;
    private boolean[] gridArray;

    public FigurePanel() {
        setLayout(new GridLayout(rowsNumber, rowsNumber, 1, 1));
        setBackground(new Color(0x000000));
        gridArray = new boolean[rowsNumber * rowsNumber];
        for (int i = 0; i < rowsNumber * rowsNumber; i++) {
            grid = new JPanel();
            grid.setBackground(new Color(0xFFFFFF));
            String name = Integer.toString(i);
            grid.setName(name);
            if (i == 0) {
                originalColor = grid.getBackground();
            }
            grid.setPreferredSize(size);
            add(grid);
        }
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                JPanel panel = (JPanel) getComponentAt(e.getPoint());
                if (panel == null || panel == FigurePanel.this) {
                    return;
                }
                if (gridArray[Integer.parseInt(panel.getName())]) {
                    panel.setBackground(originalColor);
                    panel.revalidate();
                    panel.repaint();
                } else {
                    gridArray[Integer.parseInt(panel.getName())] = true;
                    panel.setBackground(selectionColor);
                    panel.revalidate();
                    panel.repaint();
                }

            }
        });
    }

    public boolean[] getGridArray() {
        return gridArray;
    }
}

Sorry for my terrible english.