public CromTreeWidget() {
modelBuilder = new CromTreeModelBuilder();
modelBuilder.setIncludeLeafNodes(true);
tree = createEmptyTree();
selectionSource = new TreeSelectionSource(tree);
selectionSource.setNodeObjectConverter(new NodeObjectConverterImpl(disabledNodes));
explodingNodes = new ConcurrentHashMap<CromTreeNode, Boolean>();
contextMenuService = new ContextMenuService(tree, selectionSource);
}