TabPanel + FormPanel problem

[mrjoe]

If I try to create FormPanel inside TabPanel I get strange layout behavior.

How it looks when I call show() on window for the first time:
1st.png

When I show window for the second time I get correct layout.
2nd.png

    private TextField titleText;
    private TextArea abstractText;
    private TextField doiText;
    private TextButton saveButton;
    private Window window;

    public ArticleWindowView()
    {
        initialize();
    }

    private void initialize()
    {
        window = new Window();
        window.setPixelSize(800, 500);
        window.setPlain(true);
        window.setModal(true);
        window.setBlinkModal(true);
        window.setHeadingText("Article");

        createTabs();

        saveButton = new TextButton("Save");
        window.addButton(saveButton);

        TextButton b = new TextButton("Close");
        b.addSelectHandler(new SelectHandler()
        {

            @Override
            public void onSelect(SelectEvent event)
            {
                window.hide();
            }
        });
        window.addButton(b);
    }

    private void createTabs()
    {
        TabPanel tabPanel = new TabPanel();
        tabPanel.setAnimScroll(true);
        tabPanel.setPlain(true);

        window.setWidget(tabPanel);

        initGeneralTab(tabPanel);
        initFileTab(tabPanel);
    }

    private void initGeneralTab(TabPanel tabPanel)
    {
        VerticalLayoutContainer p = new VerticalLayoutContainer();
        p.setLayoutData(new MarginData(8));
        tabPanel.add(p, "General");

        titleText = new TextField();
        p.add(new FieldLabel(titleText, "Title"));
        abstractText = new TextArea();
        p.add(new FieldLabel(abstractText, "Abstract"), new VerticalLayoutContainer.VerticalLayoutData(-18, -100));
    }

    private void initFileTab(TabPanel tabPanel)
    {
        final VerticalPanel verticalPanel = new VerticalPanel();
        verticalPanel.setLayoutData(new MarginData(8));
        tabPanel.add(verticalPanel, "Files");

        final FramedPanel framedPanel = new FramedPanel();
        framedPanel.setHeadingText("File Upload Example");
        framedPanel.setButtonAlign(BoxLayoutPack.CENTER);
        framedPanel.setWidth(350);
        verticalPanel.add(framedPanel);


        final FormPanel formPanel = new FormPanel();
        formPanel.setAction("myurl");
        formPanel.setEncoding(Encoding.MULTIPART);
        formPanel.setMethod(Method.POST);
        framedPanel.add(formPanel);

        VerticalLayoutContainer p = new VerticalLayoutContainer();
        formPanel.add(p);

        TextField firstName = new TextField();
        firstName.setAllowBlank(false);
        p.add(new FieldLabel(firstName, "Name"), new VerticalLayoutData(-18, -1));

        final FileUploadField fileField = new FileUploadField();
        // file.setAllowBlank(false);
        fileField.setName("uploadedfile");
        p.add(new FieldLabel(fileField, "File"), new VerticalLayoutData(-18, -1));

        TextButton btn = new TextButton("Reset");
        framedPanel.addButton(btn);

        btn = new TextButton("Submit");
        framedPanel.addButton(btn);


    }

    public void show()
    {
        window.show();
    }