I am now creating a JTree which displays XML file while I am now using xerces-J 1.4.4. in my JTree, the user can add the node or remove the node of the JTree. I want that right click on a node of JTree will display a popup menu. This menu has the name of the node which allows to be added. However, how can I check whether the change of the JTree is valid? for example, in the add case of element to JTree, I want to check whether the new node allows to be added in that place. Any idea? thanks!