/// <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); }