EDIT

package eu.etaxonomy.cdm.vaadin.ui;

import com.vaadin.annotations.Theme;

import com.vaadin.annotations.Widgetset;

import com.vaadin.server.VaadinRequest;

import com.vaadin.spring.annotation.SpringUI;

import com.vaadin.ui.Button;

import com.vaadin.ui.Button.ClickEvent;

import com.vaadin.ui.Label;

import com.vaadin.ui.UI;

import com.vaadin.ui.VerticalLayout;

@Theme("edit")

@SpringUI(path="")

@Widgetset("eu.etaxonomy.cdm.vaadin.AppWidgetSet")

@SuppressWarnings("serial")

public class CheckTestUI extends UI {

    @Override

    protected void init(VaadinRequest request) {

        final VerticalLayout layout = new VerticalLayout();

        layout.setMargin(true);

        setContent(layout);

        Button button = new Button("Click Me");

        button.addClickListener(new Button.ClickListener() {

            @Override

            public void buttonClick(ClickEvent event) {

                layout.addComponent(new Label("Thank you for clicking"));

            }

        });

        layout.addComponent(button);

    }

}