protected override void OnPreviewKeyDown()

in tools/Explorer/TabControl/TabControl.cs [451:506]
42 lines of code
13 McCabe index (conditional complexity)

        protected override void OnPreviewKeyDown(KeyEventArgs e)
        {
            var tabsCount = GetTabsCount();
            if (tabsCount == 0)
                return;

            TabItem ti = null;

            switch (e.Key)
            {
                //case Key.Home:
                //    ti = GetTabItem(0);
                //    break;

                //case Key.End:
                //    ti = GetTabItem(tabsCount - 1);
                //    break;

                case Key.Tab:
                    if (e.KeyboardDevice.Modifiers == ModifierKeys.Control)
                    {
                        var index = SelectedIndex;
                        var direction = e.KeyboardDevice.Modifiers == ModifierKeys.Shift ? -1 : 1;

                        while (true)
                        {
                            index += direction;
                            if (index < 0)
                                index = tabsCount - 1;
                            else if (index > tabsCount - 1)
                                index = 0;

                            FrameworkElement ui = GetTabItem(index);
                            if (ui != null)
                            {
                                if (ui.Visibility == Visibility.Visible && ui.IsEnabled)
                                {
                                    ti = GetTabItem(index);
                                    break;
                                }
                            }
                        }
                    }
                    break;
            }

            TabPanel panel = Helper.FindVirtualizingTabPanel(this);
            if (panel != null && ti != null)
            {
                panel.MakeVisible(ti, Rect.Empty);
                SelectedItem = ti;

                e.Handled = ti.Focus();
            }
            base.OnPreviewKeyDown(e);
        }