Subwindow can't be called correctly by buttonClick

Vaadin 6 / 7 / 8 Framework UI
1

Hi Vaadin!

I try to call a subwindow (depending on your book of vaadin, chapter 6.7) with this code:

     removeSubjectButton.addClickListener(new ClickListener() {
        @Override
        public void buttonClick(ClickEvent event) {
           
            Object nextId = subjectUiTable.nextItemId(subjectUiTable.getValue());

            if (nextId != null) {

                subjectBeanContainer.removeItem(subjectBeanContainer.getItem(subjectUiTable.getValue()).getBean());
                subjectUiTable.setValue(nextId);

            } else {
                MessageWindow messageWindow = new MessageWindow();
                messageWindow.setMessage("B Message");
                messageWindow.setVisibility(Boolean.TRUE);
                UI.getCurrent().addWindow(messageWindow);
            }
        }
    });

where MessageWindow inherits from window. So this window shows fine, if i call it from the init method, but if i execute
this shown snippet by clicking the button, the window shows up emty on the left top edge of the browser window, nontheless it
should be placed centered with a textlabel and a button, the messageWIndow is:

public class MessageWindow extends Window {

private final Label messageLabel = new Label();

public MessageWindow() {
    super("Message");
    this.center();
    this.setModal(true);
    this.setEnabled(true);
    this.setHeight("150px");
    this.setWidth("150px");       

    // Some basic content for the window
    VerticalLayout content = new VerticalLayout();
    content.addComponent(messageLabel);
    content.setMargin(true);
   
   
    // Disable the close button
    setClosable(true);

    // Trivial logic for closing the sub-window
    Button ok = new Button("OK");
    ok.addClickListener(new ClickListener() {
        @Override
        public void buttonClick(ClickEvent event) {
            close(); // Close the sub-window
        }
    });
    content.addComponent(ok);
    this.setContent(content);
    this.setVisible(false);
}

public void setVisibility(Boolean b) {
    this.setVisible(b);
}

public void setMessage(String message) {
    messageLabel.setValue(message);
}

}

most of the code is taken from vaadin examples.
It’s run inside an embedded jetty as a vaadin servlet.

Any help would be great, cuzi’m fumblin around with this for quite some while now
Regards Peter

2

OK - seems that -finally- i found a way to get this working:

i’ve to pass the callers ui instance to the subwindow and attach the subwindow to it:

public MessageWindow(HasComponents ui) {
    super("Message");

    this.center();
    this.setModal(true);
    this.setEnabled(true);
    ui.attach(); //!!!!!

//and so on

call in “mainUI”:

MessageWindow messageWindow = new MessageWindow(UI.getCurrent());

Don’t know, whether this is best practice or not, it least, it’s working now…

Peter