private Dimension layoutSize(Container parent, boolean minimum) {
        Dimension dim = new Dimension(0, 0);
        Dimension d;
        synchronized (parent.getTreeLock()) {
            int n = parent.getComponentCount();
            for (int i = 0; i < n; i++) {
                Component c = parent.getComponent(i);
                if (c.isVisible()) {
                    d = minimum ? c.getMinimumSize() : c.getPreferredSize();
                    dim.width = Math.max(dim.width, d.width);
                    dim.height += d.height;
                    if (i > 0) {
                        dim.height += this.vgap;
                    }
                }
            }
        }
        Insets insets = parent.getInsets();
        dim.width += insets.left + insets.right;
        dim.height += insets.top + insets.bottom + this.vgap + this.vgap;
        return dim;
    }