TWL BoxLayout: setMinSize() and setMaxSize() ignored?

[Mac70]

Like in topic. It seems that setMinSize(), setMaxSize() and any other attemts to modify BoxLayout and its components sizes are ignored. Can someone explain me why this happens? Example code:

Interface superclass:

package gui;

import de.matthiasmann.twl.DesktopArea;
import de.matthiasmann.twl.GUI;
import de.matthiasmann.twl.Widget;

public abstract class Interface {

    private final DesktopArea widget;
    
    Interface() {
        widget = new DesktopArea();
        
        GUI gui = new GUI(widget, InterfaceManager.getRenderer());
        gui.applyTheme(InterfaceManager.getTheme());
        
        gui.validateLayout();
    }
    
    protected void add(Widget w) {
        widget.add(w);
    }
    
    GUI getGUI() {
        return widget.getGUI();
    }
    
    protected DesktopArea getInterface() {
        return widget;
    }
    
}

Main menu:

package gui;

import de.matthiasmann.twl.*;

public class MainMenu extends Interface {
    
    MainMenu() {
        BoxLayout layout = new BoxLayout();
        layout.setMinSize(400, 100);
        layout.setMaxSize(400, 100);
        layout.setSize(400, 100);
        
        final Button button = new Button("9998");
        button.setMinSize(100, 30);
        button.setMaxSize(100, 30);
        button.setSize(100, 30);
        button.addCallback(new Runnable() {
            public void run() {
                action(button);
            }
        });
        final Button button2 = new Button("-5");
        button2.addCallback(new Runnable() {
            public void run() {
                action(button2);
            }
        });
        final EditField field = new EditField();
        
        layout.setDirection(BoxLayout.Direction.VERTICAL);
        layout.setPosition(100, 100);
        layout.add(button);
        layout.add(button2);
        layout.add(field);
        
        add(layout);
    }
    
    private void action(Button button) {
        button.setText(String.valueOf(Integer.parseInt(button.getText())+1));
    }
    
}