Form above all elemetns in VerticalLayout

I have stuffed
VerticalLayout
. Code here:

[i]
public class EventView extends VerticalLayout implements ComponentContainer,
Property.ValueChangeListener, Button.ClickListener, FormFieldFactory {

private EntityContainer<EventVdma> container;
private PagedTable table;
private Button addButton;
private Button deleteButton;
private Button editButton;
private Button saveButton;
private Button cancelButton;
private Panel toolBarPanel;
private Panel editPanel;
private Form editorForm;
private Form addForm;

}
[/i]

When I click
addButton
, I want to put
Form addForm
above all elements.

How to do that ?