gwtclass

/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */
public class Testdialog2 implements EntryPoint {

    /**
     * This is the entry point method.
     */
    public void onModuleLoad() {

        final TextBox nameField = new TextBox();
        final Button sendButton = new Button("Send");
        sendButton.addStyleName("sendButton");
        sendButton.addClickHandler(new ClickHandler() {

            @Override
            public void onClick(ClickEvent event) {
                sendMessage(nameField.getValue());
            }
        });

        nameField.setText("Message To Send Via postMessage");

        RootPanel.get().add(sendButton);
        RootPanel.get().add(nameField);

        nameField.setFocus(true);
        nameField.selectAll();

    }

    /**
     * Sends the message to the parent window of this iframe. The parent can listen to that<br>
     * events and react on it. "*" should be replaced by the
     * @param message
     */
    public native static void sendMessage(String message) /*-{
        $wnd.parent.postMessage(message, "*");
    }-*/;
}