!7

import javax.swing.tree.*;

p-substance {
  TreeNode rootNode = new DefaultMutableTreeNode;
  JTree tree = new JTree(rootNode);
  
  //tree.addTreeExpansionListener(this);
  
  tree.addTreeWillExpandListener(new TreeWillExpandListener {
    public void treeWillExpand(TreeExpansionEvent e) throws ExpandVetoException {
      print("treeWillExpand");
    }
  });
  
  showFrame(jscroll(tree));
}