When creating a tree demo according to Small Talk http://books.zkoss.org/wiki/Small_Talks/2007/August/ZK_Tree_Model
the tree is created and displays the top-level nodes, but clicking on the nodes doesn't open it. Is it a problem, for example, in the TreeDataListener?

Similarly, when constructing and displaying an in-memory tree according to Small Talk http://books.zkoss.org/wiki/ZK_Developer%27s_Reference/MVC/Model/Tree_Model - Example: In-Memory Tree with DefaultTreeModel - the tree displays but doesn't open the lower leafs.

jsp is:
<tiles:putAttribute name="body">
<z:page zscriptLanguage="java">
<z:tree id="tree" width="1100px" rows="20" hflex="1" vflex="1" model="${tm}">
<z:treecols sizable="true" width="1100px" hflex="1">
<z:treecol width="300px" label="Name"/>
</z:treecols>
</z:tree>
</z:page>

</tiles:putAttribute>

and model data is:
ArrayList al = new ArrayList();
int i = 0;
for (; i < 1000; i++)

{ Object obj = "" + i; al.add(obj); }

BinaryTreeModel tm = new BinaryTreeModel(al);

and model is:
public class BinaryTreeModel extends AbstractTreeModel {

private ArrayList _tree = null;

/**

• Constructor
• @param tree the list is contained all data of nodes.
  */
  public BinaryTreeModel(List tree) { super(tree.get(0)); _tree = (ArrayList) tree; }

// – TreeModel --//
public Object getChild(Object parent, int index) {
int i = _tree.indexOf(parent) * 2 + 1 + index;
if (i >= _tree.size())

{ return null; }

else

{ return _tree.get(i); }

}

// – TreeModel --//
public int getChildCount(Object parent) {
int count = 0;
if (getChild(parent, 0) != null)

{ count++; }
if (getChild(parent, 1) != null) { count++; }

return count;
}

// – TreeModel --//
public boolean isLeaf(Object node)

{ return (getChildCount(node) == 0); }

}