public DefaultMutableTreeNode getPreviousNode() { return null; }
public DefaultMutableTreeNode getPreviousNode() {  if (parent == null) return null;  DefaultMutableTreeNode sibling = getPreviousSibling();   if (sibling == null) return (DefaultMutableTreeNode) parent;   if (sibling.getChildCount() != 0) return sibling.getLastLeaf();   return sibling; }
	public DefaultMutableTreeNode getPreviousNode() {		return null; // TODO	} // getPreviousNode()