sclass VerticalCenterLayout > AbstractLayoutManager {
  public void layoutContainer(Container parent) {
    L<Component> components = getComponents(parent);
    if (l(components) > 1)
      ret with print("VerticalCenterLayout fail");
    
    Component c = first(components);
    if (c == null) ret;
    
    int w = parent.getWidth(), h = parent.getHeight();
    Dimension size = c.getPreferredSize();
    int y = (h-size.height)/2;
    c.setBounds(0, y, w, size.height);

    preferredSize(size);
  }
}