/// <summary>
/// Collapses siblings of <param name="Item"/>.
/// </summary>
public static void CollapseSiblings(this TreeViewItem Item)
{
var Parent = Item.GetParent().As <FrameworkElement>();
while (!Parent.Is <TreeViewItem>())
{
if (Parent == null || Parent.Is <TreeView>())
{
break;
}
Parent = Parent.GetParent().As <FrameworkElement>();
}
ItemsControlExtensions.CollapseSiblings(Parent as ItemsControl, Item);
}
