@Override
public void createPartControl(Composite aParent) {
super.createPartControl(aParent);
CommonViewer viewer = getCommonViewer();
viewer.setExpandedElements(new Object[] { clouds, fabrics });
viewer.addDoubleClickListener(new IDoubleClickListener() {
@Override
public void doubleClick(DoubleClickEvent event) {
if (!event.getSelection().isEmpty()) {
Object o = Selections.getFirstSelection(event.getSelection());
if (o instanceof HasDoubleClickAction) {