void InitializeDataBindings ()
{
if (dataBindings != null && dataBindings.Count > 0) {
bindings = new Hashtable ();
foreach (TreeNodeBinding bin in dataBindings) {
string key = GetBindingKey (bin.DataMember, bin.Depth);
if (!bindings.ContainsKey(key))
bindings [key] = bin;
}
} else
bindings = null;
}