private CheckBoxTree createTree(AttributeSelectionModel model) {
KongaTree tree = new TreeImpl(model);
tree.setPainter(new TreeDecorator());
tree.setRootVisible(false);
tree.setShowsRootHandles(true);
tree.setCellRenderer(new TreeNodeDecorRenderer());
CheckBoxTree cbt = new CheckBoxTree(tree);
cbt.checkAll();
cbt.setPopupMenuHandler(new PopupHandler());
return cbt;
}