/// <summary>
/// Initializes a new instance of the <see cref="ItemVirtualizer"/> class.
/// </summary>
/// <param name="owner"></param>
public ItemVirtualizer(ItemsPresenter owner)
{
Owner = owner;
_scrollViewer = VirtualizingPanel.FindAncestorOfType <ScrollViewer>();
if ((owner.TemplatedParent is ItemsControl ic) && !(owner.TemplatedParent is GroupItem))
{
GroupControl = new GroupController(ic, Vertical);
}