/// <summary>
            /// Called when the children of the actor types changes.
            /// </summary>
            /// <param name="sender">The source of the event.</param>
            /// <param name="e">The <see cref="PlatformGameCreator.Editor.Common.ObservableListChangedEventArgs&lt;ActorType&gt;"/> instance containing the event data.</param>
            private void Children_ListChanged(object sender, ObservableListChangedEventArgs <ActorType> e)
            {
                switch (e.ListChangedType)
                {
                case ObservableListChangedType.ItemAdded:
                    ShowItem(e.Item);
                    break;

                case ObservableListChangedType.ItemDeleted:
                    ActorTypeTreeNode deletedItem = FindItem(e.Item);
                    if (deletedItem != null)
                    {
                        deletedItem.Remove();
                    }
                    break;

                case ObservableListChangedType.ItemChanged:
                    Debug.Assert(true, "Not supported operation.");
                    break;

                case ObservableListChangedType.Reset:
                    ClearChildren();
                    foreach (ActorType child in actorType.Children)
                    {
                        ShowItem(child);
                    }
                    break;
                }
            }
        /// <summary>
        /// Handles the Click event of the addToolStripMenuItem control.
        /// Creates new actor type to the children of the selected item.
        /// </summary>
        private void addToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (treeView.SelectedNode != null)
            {
                ActorType selectedActorType = (ActorType)treeView.SelectedNode.Tag;

                ActorType newActorType = new ActorType(selectedActorType.ActorTypes)
                {
                    Name = "New Actor Type"
                };
                selectedActorType.Children.Add(newActorType);

                treeView.ExpandAll();
                ActorTypeTreeNode newTreeNode = ((ActorTypeTreeNode)treeView.SelectedNode).FindItem(newActorType);
                treeView.SelectedNode = newTreeNode;
                newTreeNode.BeginEdit();
            }
        }