public static void ExpandAll(this TreeViewItem treeViewItem, bool isExpanded = true)
{
var stack = new Stack <TreeViewItem>(treeViewItem.Containers());
while (stack.Count > 0)
{
var item = stack.Pop();
item.IsExpanded = isExpanded;
foreach (var child in item.Containers())
{
stack.Push(child);
}
}
}
