return null; //the user didn't click a node, so we just return
Object objectClicked = curPath.getLastPathComponent();
if(objectClicked.getClass() != CreationTreeNode.class)
return null; //the user didn't click a CreationTreeNode (an item, the leaf)
//now we are sure the user click an item, we may draw the panel and register for validation
CreationTreeNode node = (CreationTreeNode)curPath.getLastPathComponent();
node.getPanel().register(this);
this.getJPanelOption().removeAll();
this.getJPanelOption().add(node.getPanel(),true);
this.validate();
this.repaint();
node.getPanel().repaint();
return node;
}