Empty Space VerticalLayout

Hi,

I'am creating a Vaadin Application and have some trouble with my Layouts.
After a succesful login the following Method is called:

private void buildMainLayout() {

/* create Mainwindow */
mainWindow = new Window("Some Content");
mainWindow.setSizeFull();

/* Mainlayout */
vLayout = new VerticalLayout();
vLayout.setSpacing(true);
vLayout.setMargin(false);
vLayout.setSizeFull();

//CustumMenubar
cmsMenuBar = new CmsMenue(this);
cmsMenuBar.setWidth("100%");

/* Combobox */
ComboBox patientBox = new ComboBox();
patientBox.setWidth("100%");
patientBox.setInputPrompt("choose Person");
patientBox.setStyleName("XXXXX");

/* Label */
sessionInfo = new Label();
sessionInfo.setValue("like this");

/* Putting it all in a HLayout*/
HorizontalLayout hLayout = new HorizontalLayout();
hLayout.setWidth("100%");
hLayout.addComponent(cmsMenuBar);
hLayout.addComponent(sessionInfo);
hLayout.addComponent(patientBox);
hLayout.setExpandRatio(cmsMenuBar, 6);
hLayout.setExpandRatio(sessionInfo, 1);
hLayout.setExpandRatio(patientBox, 1);

vLayout.addComponent(hLayout);

/* Layout for Maincontent
* This is to disply different Components beneath the Menubar, when
*/
mainContent = new VerticalLayout();

vLayout.addComponent(mainContent);

mainWindow.setContent(vLayout);

setMainWindow(mainWindow);

}

Additionally i got a function which is called when a user clicks a menuitem. This function displays the choosen Component (Calendar, Form etc..).

private void setMainComponent(Component c){

mainContent.removeAllComponents();
mainContent.addComponent(c);

}

The Problem is that between the horizontal layout and the component which is displayed by the setMainComponent Function on the vertical layout (mainContent),
an empty space remains.

I have tried a setSizeFull() on all components. I've tried it too in the setMainComponent function and this results a smaller empty space, but i think this is the wrong place to call on an configuration function. And it still remains the half of the space.

I have examined my application page with Firebug and it shows a <div> which encloses the Horizontal layout, and its precisely the empty space. But dunno which layout or component it should be.

Thank you in advance,

Frederik