JAVA_GUI_TEST

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;


public class Slusac implements ActionListener{
    Frame f;

    public Slusac(Frame f){
        this.f=f;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if(e.getActionCommand().equals("a")){
            GUI.Dijalog a = new GUI.Dijalog(f);
        }
    }
}

/////////////////////////////

import java.awt.*;

public class GUI extends Frame{

    GUI(){
        super("stagod");
        Slusac s1 = new Slusac(this);
        setVisible(true);
        Button a = new Button("a");
        Button b = new Button("b");
        setSize(500,400);
        add(a);
        add(b);
        setLayout(new FlowLayout());

        a.addActionListener(s1);
        b.addActionListener(s1);
    }

    static class Dijalog extends Dialog{
        Dijalog(Frame roditelj){
            super(roditelj,"titl",true);
            setSize(150,200);
            setVisible(true);
        }
    }

}

//////////////////////////

public class aplikacija {
    public static void main(String[] args) {
        GUI g = new GUI();
    }
}