/// <summary>
/// A static event listener which is invoked if a tree's node is being
/// expanded. This event is being observed because nodes may need to
/// be created if lazy loading is active.
/// </summary>
/// <param name="sender">The processed <see cref="TreeViewBase{T}"/>
/// control.</param>
/// <param name="e">Event arguments. The <see cref="RoutedEventArgs.OriginalSource"/>
/// property provides the expanded tree node.</param>
private static void OnTreeNodeExpanded(object sender, RoutedEventArgs e)
{
TreeViewBase <T> owner = (TreeViewBase <T>)sender;
TreeViewItem treeNode = (TreeViewItem)e.OriginalSource;
owner.OnNodeExpanded(treeNode);
//do NOT mark as handled - the event may bubble up the tree:
//e.Handled = true;
}
