An extension of Vaadin SplitLayout to enable collapsing components
One or both of the SplitLayout's components can be made collapsible using
CollapsibleSplitLayout collapsibleSplitLayout = new CollapsibleSplitLayout(
new Paragraph("Primary component"),
new Paragraph("Secondary component"));
collapsibleSplitLayout.setPrimaryComponentCollapsible(true);
collapsibleSplitLayout.setSecondaryComponentCollapsible(true);