Use DisclosurePanel
package com.java2s.gwt.client; import com.google.gwt.core.client.EntryPoint; import com.google.gwt.user.client.Window; import com.google.gwt.user.client.ui.Button; import com.google.gwt.user.client.ui.ClickListener; import com.google.gwt.user.client.ui.RootPanel; import com.google.gwt.user.client.ui.Widget; import com.google.gwt.user.client.ui.HTML; import com.google.gwt.user.client.ui.DisclosurePanel; public class GWTClient implements EntryPoint{ public void onModuleLoad() { DisclosurePanel disc = new DisclosurePanel("Click to disclose something:"); disc.setContent(new HTML("This widget is is shown and hidden<br>by the " + "disclosure panel that wraps it.")); RootPanel.get().add(disc); } }