Untitled

GWT - DialogBox.center() doesn't work correctly
public class MyDialogBox extends DialogBox {

    public MyDialogBox(final String caption, final String text) {
        setText("Caption: " + caption);

        VerticalPanel inner = new VerticalPanel();
        Label msg = new Label(text);

        Button ok = new Button("Close");
        ok.addClickHandler(new ClickHandler() {
            public void onClick(ClickEvent event) {
                    MessageTextBox.this.hide();
                }
        });

        inner.add(msg);
        ScrollPanel scrollbar = new ScrollPanel(inner);
        scrollbar.setSize("640", "480");
        VerticalPanel outer = new VerticalPanel();
        outer.add(scrollbar);
        outer.add(ok);
        setWidget(outer);
    }
}

VerticalPanel mainPanel ... //MainPanel with a lot different elements, it contains panel with buttons
VerticalPanel panel ... //Panel with buttons
panel.setViewButtonHandler(new ClickHandler() {
    public void onClick(ClickEvent event) {
        MyDialogBox dialogBox = new MyDialogBox("Caption", "Some text");
        dialogBox.center();
        dialogBox.show();
     }
});
mainPanel.add(panel);