System.Windows.Controls.SelectionMultiple.Select C# (CSharp) Метод

        public bool Select(MultiSelectTreeViewItem item)
        {
            if (IsControlKeyDown)
            {
                if (treeView.SelectedItems.Contains(item.DataContext))
                {
                    return Deselect(item, true);
                }
                else
                {
                    var e = new PreviewSelectionChangedEventArgs(true, item.DataContext);
                    OnPreviewSelectionChanged(e);
                    if (e.CancelAny)
                    {
                        FocusHelper.Focus(item, true);
                        return false;
                    }

                    return SelectCore(item);
                }
            }
            else
            {
                if (treeView.SelectedItems.Count == 1 &&
                    treeView.SelectedItems[0] == item.DataContext)
                {
                    // Requested to select the single already-selected item. Don't change the selection.
                    FocusHelper.Focus(item, true);
                    lastShiftRoot = item.DataContext;
                    return true;
                }
                else
                {
                    return SelectCore(item);
                }
            }
        }